Cadence QSPI controller device tree bindings
--------------------------------------------

Required properties:
- compatible		: should be "cadence,qspi".
- reg			: 1.Physical base address and size of SPI registers map.
			  2. Physical base address & size of NOR Flash.
- clocks		: Clock phandles (see clock bindings for details).
- sram-size		: spi controller sram size.
- status		: enable in requried dts.

connected flash properties
--------------------------

- spi-max-frequency	: Max supported spi frequency.
- page-size		: Flash page size.
- block-size		: Flash memory block size.
- tshsl-ns		: Added delay in master reference clocks (ref_clk) for
			  the length that the master mode chip select outputs
			  are de-asserted between transactions.
- tsd2d-ns		: Delay in master reference clocks (ref_clk) between one
			  chip select being de-activated and the activation of
			  another.
- tchsh-ns		: Delay in master reference clocks between last bit of
			  current transaction and de-asserting the device chip
			  select (n_ss_out).
- tslch-ns		: Delay in master reference clocks between setting
			  n_ss_out low and first bit transfer
