Tegra30: Cardhu: Add pad config tables/code based on pinmux code

Pad config registers exist in APB_MISC_GP space, and control slew
rate, drive strengh, schmidt, high-speed, and low-power modes for
all of the pingroups in Tegra30. This builds off of the pinmux
way of constructing init tables to configure select pads (SDIOCFG,
for instance) during pinmux_init().

Currently, only SDIO1CFG is changed as per the TRM to work with
the SD-card slot on Cardhu.

Thanks to StephenW for the suggestion/original idea.

Signed-off-by: Tom Warren <twarren@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>