image_types_gbmc_dynamic: Set RWFS offset

This is useful so that we don't need different partition files for
different SPI sizes. RWFS was the only variable we weren't setting
dynamically.

Tested: Built and image and the offset doesn't change

Google-Bug-Id: 351901052
Change-Id: I82c72aa679144577db3ac35c8d51b86faafa7663
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/classes/image_types_gbmc_dynamic.bbclass b/classes/image_types_gbmc_dynamic.bbclass
index 3a088ac..30f785a 100644
--- a/classes/image_types_gbmc_dynamic.bbclass
+++ b/classes/image_types_gbmc_dynamic.bbclass
@@ -15,6 +15,7 @@
     -e "$(rexpr image-descriptor ${FLASH_IMAGE_DESC_OFFSET} ${FLASH_KERNEL_OFFSET})" \
     -e "$(rexpr kernel ${FLASH_KERNEL_OFFSET} ${FLASH_ROFS_OFFSET})" \
     -e "$(rexpr rofs ${FLASH_ROFS_OFFSET} ${FLASH_EMPTY_OFFSET})" \
+    -e "$(rexpr rwfs ${FLASH_RWFS_OFFSET} ${FLASH_RWFS_END})" \
     -e "$(rexpr hoth-mailbox ${FLASH_HOTH_MAILBOX_OFFSET} ${FLASH_HOTH_MAILBOX_END})" \
     -e "$(rexpr hoth-update ${FLASH_HOTH_UPDATE_OFFSET} ${FLASH_HOTH_UPDATE_END})" \
     -e "$(rexpr hoth-secondary ${FLASH_HOTH_SECONDARY_OFFSET} ${FLASH_HOTH_SECONDARY_END})" \