UBIFS: print useful debugging messages when cannot recover gc_lnum
UBIFS: print useful debugging messages when cannot recover gc_lnum

If we fail to recover the gc_lnum we just return an error and it then
it is difficult to figure out why this happened. This patch adds useful
debugging information which should make it easier to debug the failure.

Signed-off-by: Artem Bityutskiy <19b5733dcea388885746d36043d3568bba5b4df7@nokia.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs