mtd: cfi: Add early fixup for S70GL02GS

mtd: cfi: Add early fixup for S70GL02GS

S70GL02GS flash reports a single 256 MiB chip, but is really made up
of two 128 MiB chips with 1024 sectors each.

Without early fixups (top half of device cannot be written or erased):
  ff0000000.nor-boot: Found 1 x16 devices at 0x0 in 16-bit bank. <snip>
  Amd/Fujitsu Extended Query Table at 0x0040
    Amd/Fujitsu Extended Query version 1.5.
  number of CFI chips: 1

With early fixups (entire device can be written and erased):
  Bad S70GL02GS CFI data; adjust to detect 2 chips
  ff0000000.nor-boot: Found 1 x16 devices at 0x0 in 16-bit bank. <snip>
  ff0000000.nor-boot: Found 1 x16 devices at 0x8000000 in 16-bit bank
  Amd/Fujitsu Extended Query Table at 0x0040
    Amd/Fujitsu Extended Query version 1.5.
  number of CFI chips: 2

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>