PRCM cleanup - remove prcm-regs.h

These patches clean up PRCM register access in the OMAP2 tree. Highlights:

- PRCM registers are divided into module-shared registers and global registers. Module-shared registers can appear in multiple PRCM subsystems at identical address offsets, while global registers control system-wide PRCM functions and appear only once in PRCM space.

- PRCM registers are further separated into two categories, PRM (power/reset management) and CM (clock management) registers. This is to prepare for OMAP3430 PRCM code -- PRM and CM registers share the same address space on 2420 and 2430, but exist in separate address spaces on 3430.

- Read/write functions are defined for each of the combinations above:
prm_{read,write}_reg() for PRM global registers, prm_{read,write}_mod_reg() for PRM module-shared registers, cm_{read,write}_reg() for CM global registers,
cm_{read,write}_mod_reg() for CM module-shared registers. _reg()
functions use a single (void __iomem *) to refer to global registers, and _mod_reg() functions use both a module offset and a register offset to refer to module-shared registers. Almost all C-language PRCM register access in the mach-omap2/ directory is converted to use these functions. If debugging is enabled, all PRM/CM register writes will be logged to the console.

- Symbolic constants are defined for PRCM register addresses. Registers that are shared between architectures are simply defined as-is, e.g., 'CM_CLKSEL', but registers that only exist on specific architectures have the architecture name prepended, e.g., 'OMAP2430_CM_ICLKEN3'. This aids in identifying code that must be modified for cross-platform use. Existing C code is converted to use these new constants.

- Symbolic constants are also defined for PRCM register bits, and existing C code that used 'magic numbers' for these bits is converted to use the symbolic defines. This resulted in a major improvement in code readability. As above, bits shared between architectures are labeled with only their 'base name,' but architecture-specific bits have the architecture name prepended, making it easy to identify code that will need to be changed for new architectures.

An overview of this patch series:

- Patches 1-9 add constants for PRCM modules, 24xx PRM and CM registers, 24xx PRM and CM register bits, and the register read/write functions.

- Patches 10-17 convert existing code to use the PRCM framework introduced in patches 1-9.

- Patch 18 removes prcm-regs.h.

Comments welcome.

- Paul