phy: make PHY_COMMON_PROPS Kconfig symbol conditionally user-selectable

Geert reports that enabling CONFIG_KUNIT_ALL_TESTS shouldn't enable
features that aren't enabled without it. That isn't what "*all* tests"
means, but as the prompt puts it, "All KUnit tests with satisfied
dependencies".

The impact is that enabling CONFIG_KUNIT_ALL_TESTS brings features which
cannot be disabled as built-in into the kernel.

Keep the pattern where consumer drivers have to "select PHY_COMMON_PROPS",
but if KUNIT_ALL_TESTS is enabled, also make PHY_COMMON_PROPS user
selectable, so it can be turned off.

Modify PHY_COMMON_PROPS_TEST to depend on PHY_COMMON_PROPS rather than
select it.

Fixes: e7556b59ba ("phy: add phy_get_rx_polarity() and phy_get_tx_polarity()")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/linux-phy/CAMuHMdUBaoYKNj52gn8DQeZFZ42Cvm6xT6fvo0-_twNv1k3Jhg@mail.gmail.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260226153315.3530378-1-vladimir.oltean@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/Kconfig

@@ -6,7 +6,7 @@
 menu "PHY Subsystem"
 
 config PHY_COMMON_PROPS
-	bool
+	bool "PHY common properties" if KUNIT_ALL_TESTS
 	help
 	  This parses properties common between generic PHYs and Ethernet PHYs.
 
@@ -16,8 +16,7 @@ config PHY_COMMON_PROPS
 
 config PHY_COMMON_PROPS_TEST
 	tristate "KUnit tests for PHY common props" if !KUNIT_ALL_TESTS
-	select PHY_COMMON_PROPS
-	depends on KUNIT
+	depends on KUNIT && PHY_COMMON_PROPS
 	default KUNIT_ALL_TESTS
 	help
 	  This builds KUnit tests for the PHY common property API.