phy: enter drivers/phy/Makefile even without CONFIG_GENERIC_PHY

Kconfig option CONFIG_PHY_COMMON_PROPS, which builds
drivers/phy/phy-common-props.c, was intended to be selectable
independently of CONFIG_GENERIC_PHY. Yet it lives in drivers/phy/, which
is entered by the Makefile only if CONFIG_GENERIC_PHY is set.

Allow the Makefile to enter one level deeper, but stop at drivers/phy/
if CONFIG_GENERIC_PHY is unselected (i.e. do not enter vendor folders).
The other stuff from drivers/phy/Makefile except for CONFIG_PHY_COMMON_PROPS,
like CONFIG_PHY_NXP_PTN3222, all depends on CONFIG_GENERIC_PHY.

Fixes: e7556b59ba65 ("phy: add phy_get_rx_polarity() and phy_get_tx_polarity()")
Closes: https://lore.kernel.org/lkml/[e-mail]/
Reported-by: Venkat Rao Bagalkote <[e-mail]>
Debugged-by: Christophe Leroy (CS GROUP) <[e-mail]>
Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Christophe Leroy (CS GROUP) <[e-mail]>
Tested-by: Venkat Rao Bagalkote <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/Makefile

···
 obj-y				+= irqchip/
 obj-y				+= bus/
 
-obj-$(CONFIG_GENERIC_PHY)	+= phy/
+obj-y				+= phy/
 
 # GPIO must come after pinctrl as gpios may need to mux pins etc
 obj-$(CONFIG_PINCTRL)		+= pinctrl/

drivers/phy/Makefile

···
 obj-$(CONFIG_PHY_AIROHA_PCIE)		+= phy-airoha-pcie.o
 obj-$(CONFIG_PHY_NXP_PTN3222)		+= phy-nxp-ptn3222.o
 obj-$(CONFIG_PHY_SPACEMIT_K1_PCIE)	+= phy-spacemit-k1-pcie.o
-obj-y					+= allwinner/	\
+obj-$(CONFIG_GENERIC_PHY)		+= allwinner/	\
 					   amlogic/	\
 					   apple/	\
 					   broadcom/	\