net: pcs: xpcs: propagate xpcs_read error to xpcs_get_state_c37_sgmii

net: pcs: xpcs: propagate xpcs_read error to xpcs_get_state_c37_sgmii

While phylink_pcs_ops :: pcs_get_state does return void, xpcs_get_state()
does check for a non-zero return code from xpcs_get_state_c37_sgmii()
and prints that as a message to the kernel log.

However, a non-zero return code from xpcs_read() is translated into
"return false" (i.e. zero as int) and the I/O error is therefore not
printed. Fix that.

Fixes: 836cbf63391c ("net: pcs: add C37 SGMII AN support for intel mGbE controller")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220720112057.3504398-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>