The "clock-frequency" DT property is listed as optional, However,
the current code stores the return value of of_property_read_u32 in
the return code of mv64xxx_of_config, but then forgets to clear it
after setting the default value of "clock-frequency". It is then
passed out to the main probe function, resulting in a probe failure
when "clock-frequency" is missing.

This patch checks and then throws away the result of
of_property_read_u32, instead of storing it and having to clear it
afterwards.

This issue was discovered after the property was removed from all
sunxi DTs.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Cc: stable@vger.kernel.org
Merge branch 'i2c-clock-fix'