drivers/rtc/rtc-mxc.c: remove unneeded label

There is no need to jump to the 'exit_free_pdata' label when
devm_clk_get() fails, as we can directly return the error and simplify the
code a bit.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>