spi: davinci: remove unused variable 'pdata'

The 'pdata' variable is unused in couple of routines.

Remove such occurences.

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Tested-By: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>