staging: sm750fb: Refine the code and remove unused code.

Every call to the function waitNextVerticalSync() used the macro
primaryWaitVerticalSync(), so the macro was removed and the function
waitNextVerticalSync() renamed to primary_wait_vertical_sync().

With this change, an unnecessary 'if' statement was removed together
with the lines within the 'else' statement, because it was never
satisfied.

The modified function was refined to better match the Kernel coding
style.

Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>