rsi: Changes to sdio reads and writes

SDIO read or write maximum size is limited to 2^16. This is done to make
the host interface operations common for SDIO and USB.

Signed-off-by: Prameela Rani Garnepudi <prameela.j04cs@gmail.com>
Signed-off-by: Amitkumar Karwar <amit.karwar@redpinesignals.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>