mtd-utils: upgrade 2.1.4 -> 2.1.5

Raw short log since the 2.1.4 release:

Alex Henrie (1):
       mkfs.jffs2: fix spelling of --compression-mode parameter in help text

Andrew Mellor (1):
       ubinfo: Fix --vol_id return code for absent volume id

Christophe Kerello (1):
       nandflipbits: fix corrupted oob

David Oberhollenzer (1):
       Release mtd-utils-2.1.5

Enrico Jorns (1):
       libmtd: do not ignore non-zero eraseblock size when MTD_NO_ERASE is set

Frederic Germain (2):
       .gitignore: add new ubiscan utility
       Fix warning about unaligned pointer in jffs2reader

Khem Raj (1):
       tests: Remove unused linux/fs.h header from includes

Michael Walle (1):
       mtd-utils: flash_otp_dump make offset optional

Mike Frysinger (1):
       fix test bashism

Rafał Miłecki (1):
       nandwrite: warn about writing 0xff blocks

Sascha Hauer (1):
       mtd-utils: nanddump: fix writing big images on 32bit machines

liaohua (1):
       nor-utils: fix memory leak

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit a3289c98)
Signed-off-by: Steve Sakoman <steve@sakoman.com>