cleanups for efi.c

These trivial patches clean up efi.c. There are no functionality changes introduced by these patches.

1/4 - fix whitespace, fit in 80 columns, repair some indentation 2/4 - spelling and punctuation
3/4 - add /* never reached */ to a couple returns
4/4 - use a #define to reduce code duplication

Of these, I only intended to create 1/4, the others were just byproducts... In particular, I'm ambivalent about 4/4. It reduces code duplication and makes things easier to read, but does so by introducing a #define, so it's a bit of a toss-up.

Aron