Optimized spi-flash bar writing code and also removed
unnecessary bank_sel in read_ops.

Cc: Simon Glass <sjg@chromium.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>