mtd: cfi: cmdset_0001: Do not allow read/write to suspend erase block.

mtd: cfi: cmdset_0001: Do not allow read/write to suspend erase block.

[ Upstream commit 6510bbc88e3258631831ade49033537081950605 ]

Currently it is possible to read and/or write to suspend EB's.
Writing /dev/mtdX or /dev/mtdblockX from several processes may
break the flash state machine.

Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>