regulator: bd718x7: Make some variable static

regulator: bd718x7: Make some variable static

Fix sparse warnings:

drivers/regulator/bd718x7-regulator.c:576:28: warning: symbol 'bd71847_swcontrol_ops' was not declared. Should it be static?
drivers/regulator/bd718x7-regulator.c:585:28: warning: symbol 'bd71847_hwcontrol_ops' was not declared. Should it be static?
drivers/regulator/bd718x7-regulator.c:902:28: warning: symbol 'bd71837_swcontrol_ops' was not declared. Should it be static?
drivers/regulator/bd718x7-regulator.c:913:28: warning: symbol 'bd71837_hwcontrol_ops' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-By: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/20200910034240.37268-1-yuehaibing@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>