net: stmmac: mdio: remove redundant clock rate tests

The pattern:

	... if (v < A)
		...
	else if (v >= A && v < B)
		...

can be simplified to:

	... if (v < A)
		...
	else if (v < B)
		...

which makes the string of ifelse more readable.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Mohd Ayaan Anwar <quic_mohdayaa@quicinc.com>
Link: https://patch.msgid.link/E1uu8oc-00000001vpN-0S1A@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>