net: stmmac: qcom-ethqos: correct prg_rclk_dly comment

net: stmmac: qcom-ethqos: correct prg_rclk_dly comment

The comment for calculating the prg_rclk_dly value is incorrect as it
omits the brackets around the divisor. Add the brackets to allow the
reader to correctly evaluate the value. Validated with the values given
in the driver.

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/E1w62ny-0000000E3D8-38Yp@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>