arm: vp9mc: Insert a literal pool at the middle of the file

This fixes errors like this when building non-pic binaries with armv6
as baseline:

Error: invalid literal constant: pool needs to be closer
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/arm/vp9mc_neon.S

@@ -484,6 +484,7 @@ do_8tap_h_filters 16
 do_8tap_h_filters 8
 do_8tap_h_filters 4
 
+.ltorg
 
 @ Vertical filters