mmc: omap: align adma and dma table entries

mmc->max_segs to core layer was set to 1024, but
adma table entry could only hold 512 entries. Increase
adma table entry size to 1024 from 512 to avoid mismatch.

Also set max_blk_count, max_req_size to what adma can
handle.

Change-Id: I8e08ee39bfa966bdf8a6c4374aea82b34fedcc62
Signed-off-by: Viswanath Puttagunta <vishp@ti.com>