init/: delete hard-coded setting and testing of BUILD_CRAMDISK

There seems to be little point in explicitly setting, then testing the macro
BUILD_CRAMDISK within the context of a single source file.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>