Fix issue with rtc device not getting unregistered in probe error path.

Use the devres managed resource functions in the probe routine to cleanup
the error path.

Use sysfs_{create/remove}_group to add/remove the sysfs files.

Reduces the text size by 132 bytes, increases data by 12 bytes:
    text	   data	    bss	    dec	    hex	filename
-    937	    124	      0	   1061	    425	rtc-ep93xx.o
+    805	    136	      0	    941	    3ad	rtc-ep93xx.o
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>