ARM: 8343/1: VDSO: add build artifacts to .gitignore

vdsomunge and vdso.so.raw are outputs that don't get matched by the
normal ignore rules.
Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/vdso/.gitignore

 vdso.lds
+vdso.so.raw
+vdsomunge