spi: zynq_qspi: Add SPI memory operations to zynq qspi

spi: zynq_qspi: Add SPI memory operations to zynq qspi

Spi memory operation interface is added to zynq qspi
driver to provide an high-level interface to execute
qspi controller specific memory operations by avoiding
spi_mem_exec_op() from spi-mem framework.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Link: https://lore.kernel.org/r/20220131052240.23403-5-ashok.reddy.soma@xilinx.com
Signed-off-by: Michal Simek <michal.simek@xilinx.com>