memory: omap-gpmc: fix coverity issue "Control flow issues"

Assign a big positive integer instead of an negative integer to an
u32 variable. Also remove the check for ">= 0" which doesn't make sense
for unsigned integers.
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1527139 ("Control flow issues")
Fixes: 89aed3cd ("memory: omap-gpmc: wait pin additions")
Signed-off-by: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20221109102454.174320-1-benedikt.niedermayr@siemens.comSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

drivers/memory/omap-gpmc.c

@@ -1045,7 +1045,7 @@ EXPORT_SYMBOL(gpmc_cs_free);
 
 static bool gpmc_is_valid_waitpin(u32 waitpin)
 {
-	return waitpin >= 0 && waitpin < gpmc_nr_waitpins;
+	return waitpin < gpmc_nr_waitpins;
 }
 
 static int gpmc_alloc_waitpin(struct gpmc_device *gpmc,

include/linux/platform_data/gpmc-omap.h

@@ -137,11 +137,11 @@ struct gpmc_device_timings {
 #define GPMC_MUX_AD			2	/* Addr-Data multiplex */
 
 /* Wait pin polarity values */
-#define GPMC_WAITPINPOLARITY_INVALID -1
+#define GPMC_WAITPINPOLARITY_INVALID UINT_MAX
 #define GPMC_WAITPINPOLARITY_ACTIVE_LOW 0
 #define GPMC_WAITPINPOLARITY_ACTIVE_HIGH 1
 
-#define GPMC_WAITPIN_INVALID -1
+#define GPMC_WAITPIN_INVALID UINT_MAX
 
 struct gpmc_settings {
 	bool burst_wrap;	/* enables wrap bursting */