Get rid of optional clock as that is now managed by the
AHCI platform driver.

Correct .mpu_rt_idx to 1 as the module register space (SYSCONFIG..)
is passed as the second memory resource in the device tree.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Reviewed-by: Rajendra Nayak <rnayak@ti.com>
Tested-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>