net: phy: fix sign type error in genphy_config_eee_advert

net: phy: fix sign type error in genphy_config_eee_advert

[ Upstream commit 3bb9ab63276696988d8224f52db20e87194deb4b ]

In genphy_config_eee_advert, the return value of phy_read_mmd_indirect is
checked to know if the register could be accessed but the result is
assigned to a 'u32'.
Changing to 'int' to correctly get errors from phy_read_mmd_indirect.

Fixes: d853d145ea3e ("net: phy: add an option to disable EEE advertisement")
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>