phosphor: image_types_phosphor: flash overrides

Add an override based on FLASH_SIZE, for use with the hardcoded offsets
that exist when building raw flash images.

This lets us have different flash layouts for different size flash
modules that can be shared between machines.

The existing 32MiB layouts are unchanged:
  partition: size: offset

  u-boot: 384 KiB (0 KiB)
  u-boot-env: 128 KiB (384 KiB)
  kernel/FIT: 4352 KiB (512 KiB)
  rootfs: 23808 KiB (4864 KiB)
  rwfs: 4MiB (28672 KiB)

The new layout is as follows:
  partition: size: offset

  u-boot: 896 KiB (0 KiB)
  u-boot-env: 128 KiB (896 KiB)
  kernel/FIT: 9 MiB (1 MiB)
  rootfs: 86 MiB (10 MiB)
  rwfs: 32MiB (96 MiB)

Change-Id: I35c413eafe73443253f487035bbaf5e004e2da3f
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/classes/phosphor-software-manager-ubi-fs.bbclass b/classes/phosphor-software-manager-ubi-fs.bbclass
index 6b0a78e..0280133 100644
--- a/classes/phosphor-software-manager-ubi-fs.bbclass
+++ b/classes/phosphor-software-manager-ubi-fs.bbclass
@@ -41,7 +41,10 @@
 BMC_RW_MTD ??= "bmc"
 BMC_RO_MTD ??= "bmc"
 BMC_KERNEL_MTD ??= "bmc"
+FLASH_SIZE ?= "32768"
+DISTROOVERRIDES .= ":flash-${FLASH_SIZE}"
 BMC_RW_SIZE ??= "0x600000"
+BMC_RW_SIZE_flash-131072 = "0x2000000"
 SYSTEMD_SUBSTITUTIONS += "RW_MTD:${BMC_RW_MTD}:obmc-flash-bmc-ubirw.service"
 SYSTEMD_SUBSTITUTIONS += "RO_MTD:${BMC_RO_MTD}:obmc-flash-bmc-ubiro@.service"
 SYSTEMD_SUBSTITUTIONS += "KERNEL_MTD:${BMC_KERNEL_MTD}:obmc-flash-bmc-ubiro@.service"