spi/dw_spi: enable platform specific chipselect.
spi/dw_spi: enable platform specific chipselect.

The driver core allows for a platform-specific chipselect assert/deassert
function, however the chipselect function in the core doesn't take advantage
of this fact.

This enables the use of a custom function, should it be defined.

Signed-off-by: George Shore <9fd8de5fc2a7c2c0d469b2fff1afde4e5def37ba@georgeshore.com>
Signed-off-by: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@secretlab.ca>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas