drivers: gpio: Fix Coverity static scan issues

patch fix the dead code issue reported by coverity static scan
for gpio driver of cc2650 TI SOC. CC2650_IOC_NO_PULL macro
is defined Zero, bitwise and with any value would result to
zero,because of which only false condition of if is evaluated
but not the true condition.

Jira ZEP-2469.

Signed-off-by: Savinay Dharmappa <savinay.dharmappa@intel.com>