staging: sm750fb: fix c99 comments

fixed all checkpatch.pl ERROR: do not use C99 // comments

Any C99 comments used to comment out code are simply removed.
Also some of the errors occur inside '#if 0' blocks which I
might as well fix since checkpatch.pl caught them but the blocks
themselves should probably be cleaned up later.

Changes since v1: close a comment block

Signed-off-by: Juston Li <juston.h.li@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>