mtd: jedec_probe: initialise make sector erase command variable

In the commit 08968041
 (mtd: cfi_cmdset_0002: make sector erase command variable)
introdused a field sector_erase_cmd. In the same commit initialisation
of cfi->sector_erase_cmd made in cfi_chip_setup()
(file drivers/mtd/chips/cfi_probe.c), so the CFI chip has no problem:

...
        cfi->cfi_mode = CFI_MODE_CFI;
        cfi->sector_erase_cmd = CMD(0x30);
...

But for the JEDEC chips this initialisation is not carried out,
so the JEDEC chips have sector_erase_cmd == 0.

This patch adds the missing initialisation.

Signed-off-by: Antony Pavlov <antony@niisi.msk.ru>
Acked-by: Guillaume LECERF <glecerf@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
CC: stable@kernel.org