mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
have PBIAS regulator) in order for MMC1 to work.

Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
using a olddefconfig or a custom .config.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>