package/ti-gfx: do not forcefully remove source dir on extract

ti-gfx uses custom extract commands, which first and foremost removes
the source dir unconditionally.

Thee side-effect of this is that make will re-extract, re-patch and
probably re-build ti-gfx at each run.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Spenser Gilliland <spenser@gillilanding.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/ti-gfx/ti-gfx.mk

@@ -90,7 +90,6 @@ TI_GFX_HDR_DIRS = OGLES2/EGL OGLES2/EWS OGLES2/GLES2 OGLES2/KHR \
 	OGLES/GLES bufferclass_ti/ pvr2d/ wsegl/
 
 define TI_GFX_EXTRACT_CMDS
-	$(RM) -rf $(TI_GFX_DIR)
 	chmod +x $(DL_DIR)/$(TI_GFX_SOURCE)
 	printf "Y\nY\n qY\n\n" | $(DL_DIR)/$(TI_GFX_SOURCE) \
 		--prefix $(@D) \