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 <[e-mail]>
Addresses-Coverity-ID: 1527139 ("Control flow issues")
Fixes: 89aed3cd5cb9 ("memory: omap-gpmc: wait pin additions")
Signed-off-by: Benedikt Niedermayr <[e-mail]>
Reviewed-by: Roger Quadros <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

drivers/memory/omap-gpmc.c

···
 
 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

···
 #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 */