mtd: cfi_cmdset_0002: Change erase one block to enable XIP once

To enable XIP it is executed both normal and error cases.
This call can be moved after the for loop as same with erase chip.

Signed-off-by: Tokunori Ikegami <ikegami@allied-telesis.co.jp>
Reviewed-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>