staging: sm750fb: change definition of HWC_LOCATION fields

Use BIT() macro for single-bit fields of HWC_LOCATION register and
define HWC_LOCATION_{X,Y}_MASK for masking the address bits.

Signed-off-by: Mike Rapoport <mike.rapoport@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>