Increase rootfs size to 2.5GB.

Change-Id: Ia7412265338e04aa81259b08275bb93162d86acf
diff --git a/arch.mk b/arch.mk
index fbfe683..77584ac 100644
--- a/arch.mk
+++ b/arch.mk
@@ -19,6 +19,6 @@
 BOARD_PACKAGES_EXTRA :=
 
 BOOT_SIZE_MB := 128
-ROOTFS_SIZE_MB := 2048
+ROOTFS_SIZE_MB := 2560
 
 BOARD_NAME := excelsior