staging/sm7xxfb: select sm7xxfb only when CONFIG_PCI is enabled

the sm7xxfb is a pci device, and should depend on the PCI. And also if we wont' depend on the PCI sub-system, the following warns will be triggered,

drivers/staging/sm7xxfb/sm7xxfb.c:1061:1: warning: data definition has no type or storage class [enabled by default] drivers/staging/sm7xxfb/sm7xxfb.c:1061:1: warning: type defaults to 'int' in declaration of 'module_pci_driver' [-Wimplicit-int] drivers/staging/sm7xxfb/sm7xxfb.c:1061:1: warning: parameter names (without types) in function declaration [enabled by default]

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Hello Fengguang Wu,

I think this solves the build warnings told by you, sorry for my bad english :(.

 drivers/staging/sm7xxfb/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index d5013f8..e2922ae 100644
@@ -1,6 +1,6 @@
 config FB_SM7XX
 	tristate "Silicon Motion SM7XX framebuffer support"
-	depends on FB
+	depends on FB && PCI
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT

1.7.9.5