memdesc: Fix warning when comparing signed and unsigned expressions
memdesc: Fix warning when comparing signed and unsigned expressions

Cast value to unsigned before comparing with signed constants. As we are
checking if value is lower than 0 before comparing, we won't cast
negative numbers.

Signed-off-by: Otavio Pontes <a04f37e3ccb281cf4119e4b2fa8286ed94121d92@intel.com>

otaviobp/soletta,otaviobp/soletta,otaviobp/soletta,otaviobp/soletta,otaviobp/soletta,otaviobp/soletta