memory: omap-gpmc: fix wait pin validation

This bug has been introduced after switching from -1 to UINT_MAX
for GPMC_WAITPIN_INVALID.

The bug leads to an error when the optional gpmc,wait-pin
dt-property is not used:

...
gpmc_cs_program_settings: invalid wait-pin (-1)
...

Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
Fixes: 8dd7e4af58 ("memory: omap-gpmc: fix coverity issue "Control flow issues"")
Acked-by: Roger Quadros <rogerq@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20221209112828.581491-1-benedikt.niedermayr@siemens.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

drivers/memory/omap-gpmc.c

@@ -1918,7 +1918,8 @@ int gpmc_cs_program_settings(int cs, struct gpmc_settings *p)
 		}
 	}
 
-	if (p->wait_pin > gpmc_nr_waitpins) {
+	if (p->wait_pin != GPMC_WAITPIN_INVALID &&
+	    p->wait_pin > gpmc_nr_waitpins) {
 		pr_err("%s: invalid wait-pin (%d)\n", __func__, p->wait_pin);
 		return -EINVAL;
 	}