mfd: htc-i2cpld: Use '!variable' instead of 'variable == NULL'
mfd: htc-i2cpld: Use '!variable' instead of 'variable == NULL'

This aids in consistency, as the rest of the checks in the file use this
notation.

Signed-off-by: Lee Jones <630e34333487a351a857f6b705e04d30b37c1629@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs