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.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>