phy: enter drivers/phy/Makefile even without CONFIG_GENERIC_PHY

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/43ea0202-891d-4582-980b-5cb557b41114@linux.ibm.com/
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Debugged-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://patch.msgid.link/20260123110600.3118561-1-vladimir.oltean@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>