ANDROID: memory_state_time: fix undefined behavior with missing DT properties

kernelci reports warnings about unintialized variable usage:

drivers/misc/memory_state_time.c:351:12: warning: 'lenf' is used uninitialized in this function [-Wuninitialized]
drivers/misc/memory_state_time.c:321:14: warning: 'lenb' is used uninitialized in this function [-Wuninitialized]

In both cases we try to continue without a DT property but use the
length that has not been assigned at this point. This rearranges the
code in the two functions to bail out earlier in case of an error.

The patch is needed for both android-common-4.9, 4.4 and 3.18.

Link: https://kernelci.org/build/id/591177f459b5147648b12d54/logs/


Fixes: ad3c02f8 ("ANDROID: Implement memory_state_time, used by qcom,cpubw")
Cc: James Carr <carrja@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>