mmc: host: omap_hsmmc: return error if any of the regulator APIs fail

Return error if any of the regulator APIs (regulator_enable,
regulator_disable, regulator_set_voltage) fails in
omap_hsmmc_set_power to avoid undefined behavior.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>