clk: microchip: mpfs: Fix error detection

clk: microchip: mpfs: Fix error detection

clk_register() will return standard error codes so the use of ERR_PTR()
is incorrect. Furthermore the code was ineffective as it lacked a return
statement that would have actually made use of the result. Add the
return statement and remove the use of ERR_PTR to correct this.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>