mmc: sdhci: Balance vmmc regulator_disable()

As a follow-up of commit
"mmc: sdhci: Balance vmmc regulator_enable(), and always enable vqmmc"
vmmc regulator disable is also not needed in sdhci_remove_host.
The regulator is completely controlled by mmc_power_up and mmc_power_off
functions and is already disabled by the time of removing the host.
Extra regulator_disable call in sdhci_remove_host is unbalanced and
causes a warning reported by regulator core, so should be removed.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>