mmc: cqhci: Set task descriptor size capability before allocation

If cypto is supported by mmc controller, task descriptor length
should be 128 bit independent of architecture.
But currently without this fix, for 32bit architecture task
descriptor length is set as 64 bit only as capability is checked
after allocation of descriptor memory.

To fix this, set task descriptor size capability before allocating
descriptor table.

Change-Id: I144080fdf2ecc074dfe48f375546570856795b42
Signed-off-by: Ram Prakash Gupta <rampraka@codeaurora.org>