net: rswitch: Fix error detection

net: rswitch: Fix error detection

In rswitch_probe the error detection after the call to devm_clk_get is
very wrong. It checks the value of ret which is uninitialised at that
point. Instead it should be using the macros for including errors into
pointers.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>