regmap: fix coccinelle warnings

   /drivers/base/regmap/regmap.c:717:6-33: WARNING:
Comparison to bool.

   More information about semantic patching is available at
http://coccinelle.lip6.fr/

Signed-off-by: Nenghua Cao <nhcao@marvell.com>
Signed-off-by: Mark Brown <broonie@linaro.org>