net: stmmac: qcom-ethqos: simplify prg_rclk_dly programming

net: stmmac: qcom-ethqos: simplify prg_rclk_dly programming

Rather than coding the entire register update twice with different
values, use a local variable to specify the value and have one
register update statement that uses this local variable. This results
in neater code.

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/E1w62no-0000000E3Cw-2EmH@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>