regulator: cpcap-regulator: Remove declared and set, but never used variable 'ignore'

It's okay to not check the return value that you're not conserned
about, however it is not okay to assign a variable and not check or
use the result.

Fixes W=1 warnings(s):

 drivers/regulator/cpcap-regulator.c:172:13: warning: variable ‘ignore’ set but not used [-Wunused-but-set-variable]
 172 | int error, ignore;
 | ^~~~~~
 drivers/regulator/cpcap-regulator.c: In function ‘cpcap_regulator_disable’:
 drivers/regulator/cpcap-regulator.c:196:13: warning: variable ‘ignore’ set but not used [-Wunused-but-set-variable]
 196 | int error, ignore;
 | ^~~~~~

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200625163614.4001403-8-lee.jones@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>