sf: Add FSR support to spi_flash_cmd_wait_ready

sf: Add FSR support to spi_flash_cmd_wait_ready

This patch adds flag status register reading support to
spi_flash_cmd_wait_ready.

Cc: Simon Glass <[email protected]>
Cc: Marek Vasut <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Siva Durga Prasad Paladugu <[email protected]>
Cc: Stefan Roese <[email protected]>
Cc: Tom Warren <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Hou Zhiqiang <[email protected]>
Tested-by: Jagan Teki <[email protected]>
Tested-by: Bin Meng <[email protected]>
Signed-off-by: Jagan Teki <[email protected]>