phy: qcom-ufs: Fix build error due to missing export symbols

Fix below build error when compile the driver as a module.

ERROR: "ufs_qcom_phy_power_off" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_power_on" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_exit" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_calibrate" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_generic_probe" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_init_vregulators" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_init_clks" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_remove" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "get_ufs_qcom_phy" [drivers/phy/phy-qcom-ufs-qmp-20nm.ko] undefined!
ERROR: "ufs_qcom_phy_power_off" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_power_on" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_exit" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_generic_probe" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_init_vregulators" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_init_clks" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_calibrate" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "ufs_qcom_phy_remove" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
ERROR: "get_ufs_qcom_phy" [drivers/phy/phy-qcom-ufs-qmp-14nm.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>