mmc: sd: Fix sd current limit setting

Host has different current capabilities at different voltages, we need
to record these settings seperately. The defined voltages are 1.8/3.0/3.3.
For other voltages, we do not touch current limit setting.

Before we set the current limit for the sd card, find out the host's
operating voltage first and then find out the current capabilities of
the host at that voltage to set the current limit.

Signed-off-by: Aaron Lu <aaron.lu@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>