net: stmmac: qcom-ethqos: move qcom_ethqos_set_sgmii_loopback() up

ethqos_set_func_clk_en() configures both SGMII loopback and the RGMII
functional clock setting. qcom_ethqos_set_sgmii_loopback() is only
called from within ethqos_set_func_clk_en(), and checks for
PHY_INTERFACE_MODE_2500BASEX.

Move qcom_ethqos_set_sgmii_loopback() to the callers of
ethqos_set_func_clk_en() except for ethqos_configure_rgmii() where we
know that ethqos->phy_mode will not be PHY_INTERFACE_MODE_2500BASEX.

Reviewed-by: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
Tested-by: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1vuSKl-0000000ASc1-18ka@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>