ARM: fix lh7a40x build

No idea if this platform actually uses cpufreq_get(), but it doesn't
have any cpufreq drivers.  That's not to say it doesn't use cpufreq_get()
in its drivers.  LH7a40x is unmaintained anyhow, and should probably
be killed off.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>