Revert "g3: add bump script"

This reverts commit 3792b6d9564e537c34bf963c87a3ac0a7652a0fb.

	deleted:    bump/bump.py
	modified:   mkbootimg.mk
g3: add bump script

* auto bumps boot and recovery images
* to enable for your variant, set TARGET_REQUIRES_BUMP in BoardConfig

Change-Id: Ib04dda56564c8b89f9c24a75ef5dffc43073b063
Revert "g3: add bump script"

This reverts commit 3792b6d9564e537c34bf963c87a3ac0a7652a0fb.

	deleted:    bump/bump.py
	modified:   mkbootimg.mk
g3: add bump script

* auto bumps boot and recovery images
* to enable for your variant, set TARGET_REQUIRES_BUMP in BoardConfig

Change-Id: Ib04dda56564c8b89f9c24a75ef5dffc43073b063