staging: sm750fb: Change 'uint32_t' to 'u32'

It is preferred to use 'u32' instead of 'uint32_t' for unsigned int. Issue
detected by checkpatch.

Signed-off-by: Rehas Sachdeva <aquannie@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>