spi: spi-zynqmp-gqspi: Fix kernel-doc warnings

Document zynqmp_qspi ctrl and op_lock member description. It also adds
return documentation for 'zynqmp_qspi_setuprxdma' and zynqmp_qspi_read_op.

Fixes below kernel-doc warnings-

spi-zynqmp-gqspi.c:178: warning: Function parameter or member 'ctlr' not
described in 'zynqmp_qspi'
spi-zynqmp-gqspi.c:178: warning: Function parameter or member 'op_lock'
not described in 'zynqmp_qspi'

spi-zynqmp-gqspi.c:737: warning: No description found for return value of
'zynqmp_qspi_setuprxdma'
spi-zynqmp-gqspi.c:822: warning: No description found for return value of
'zynqmp_qspi_read_op'
Signed-off-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Link: https://lore.kernel.org/r/20221011062040.12116-2-amit.kumar-mahapatra@amd.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-zynqmp-gqspi.c

@@ -141,6 +141,7 @@ enum mode_type {GQSPI_MODE_IO, GQSPI_MODE_DMA};
 
 /**
  * struct zynqmp_qspi - Defines qspi driver instance
+ * @ctlr:		Pointer to the spi controller information
  * @regs:		Virtual address of the QSPI controller registers
  * @refclk:		Pointer to the peripheral clock
  * @pclk:		Pointer to the APB clock
@@ -157,6 +158,7 @@ enum mode_type {GQSPI_MODE_IO, GQSPI_MODE_DMA};
  * @genfifoentry:	Used for storing the genfifoentry instruction.
  * @mode:		Defines the mode in which QSPI is operating
  * @data_completion:	completion structure
+ * @op_lock:		Operational lock
  */
 struct zynqmp_qspi {
 	struct spi_controller *ctlr;
@@ -739,6 +741,8 @@ static irqreturn_t zynqmp_qspi_irq(int irq, void *dev_id)
 /**
  * zynqmp_qspi_setuprxdma - This function sets up the RX DMA operation
  * @xqspi:	xqspi is a pointer to the GQSPI instance.
+ *
+ * Return:	0 on success; error value otherwise.
  */
 static int zynqmp_qspi_setuprxdma(struct zynqmp_qspi *xqspi)
 {
@@ -823,6 +827,8 @@ static void zynqmp_qspi_write_op(struct zynqmp_qspi *xqspi, u8 tx_nbits,
  * @rx_nbits:	Receive buswidth.
  * @genfifoentry:	genfifoentry is pointer to the variable in which
  *			GENFIFO	mask is returned to calling function
+ *
+ * Return:	0 on success; error value otherwise.
  */
 static int zynqmp_qspi_read_op(struct zynqmp_qspi *xqspi, u8 rx_nbits,
 				u32 genfifoentry)