mmc: sd: report correct speed and capacity of uhs cards

Since only UHS-I cards respond with S18A set in response to ACMD41,
we set the card as ultra-high-speed after successfull initialization.
We need to decide whether a card is SDXC based on the C_SIZE field
of CSDv2.0 register. According to Physical Layer spec v3.01, the
minimum value of C_SIZE for SDXC card is 00FFFFh.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Tested-by: Philip Rakity <prakity@marvell.com>
Acked-by: Zhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>