Commit d7e82c78d7 added a generic kernel patch that exposes a new
symbol REALTEK_PHY_HWMON when REALTEK_PHY and HWMON are enabled. The new
symbol was added to kmod-phy-realtek, but the kmod is not used in the
realtek target.
Fixes: d7e82c78d7 ("generic: backport Realtek PHY patches from upstream")
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>