msm: msm_fb: Remove broken code that attempted to align FB smem.

If passed an aligned buffer, the realignment in msm_fb_register would
offset the buffer by -4096 bytes, which caused the memory allocated
before the FB smem to be corrupted when the first 4096 bytes of the FB
were written.

This function is always passed an aligned buffer, so the useless
and broken realignment was removed, and a BUG_ON() added instead.

Change-Id: Iccc2da270ff882164a3fd7adc6a170b4c68e8fa4
Signed-off-by: Christopher Lais <chris+android@zenthought.org>
msm: msm_fb: fix an error path not releasing entry_mutex.

There was a code path for error conditions keeping a lock on
entry_mutex.  This patch corrects it to properly unlock the mutex.

Change-Id: I1cf234409760436ec8ebe6ea40a2833fe5703221
Signed-off-by: Christopher Lais <chris+android@zenthought.org>