rsi: Add new host interface operations

Host interface opearation master_reg_read, master_reg_write and
load_data_master_write are added. These functions are needed for the
new firmware loading method. As part of this, the function
master_access_msword is moved from rsi_91x_sdio_ops.c to rsi_91x_sdio.c.

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>