net: stmmac: qcom-ethqos: move loopback decision next to reg update

net: stmmac: qcom-ethqos: move loopback decision next to reg update

Move the loopback decision next to the register update, and make the
local variable unsigned. As a result, there is now no need for the
comment referring to the programming being later.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Tested-by: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
Link: https://patch.msgid.link/E1w62nt-0000000E3D2-2fWk@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>