spi: cadence: fix static checker warning

spi: cadence: fix static checker warning

This patch fixes Smatch static checker warning.
CDNS_XSPI_CMD_REG_5 is used in ACMD mode and currently
only STIG mode is enabled which doesn't use CDNS_XSPI_CMD_REG_5
and hence everything was working in STIG mode.
Since plan is to use same function cdns_xspi_trigger_command()
in ACMD mode, increasing size of the array passed to it.

Fixes: a16cc8077627 ("spi: cadence: add support for Cadence XSPI controller")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/linux-spi/20210930134231.GA14363@kili/
Signed-off-by: Parshuram Thombare <pthombar@cadence.com>
Link: https://lore.kernel.org/r/1633336704-22735-1-git-send-email-pthombar@cadence.com
Signed-off-by: Mark Brown <broonie@kernel.org>