libswscale: arm: Don't assume aligned output in yuv2rgb functions

This fixes failures in recently added checkasm tests.

While the buffers in most cases are aligned, libswscale in general
can't assume the output to be aligned.

Signed-off-by: Martin Storsjö <martin@martin.st>

libswscale/arm/yuv2rgb_neon.S

@@ -75,8 +75,8 @@
     vzip.8              d7, d11                                        @ d7 = G1G2G3G4G5G6G7G8 d11 = G9G10G11G12G13G14G15G16
     vzip.8              d8, d12                                        @ d8 = B1B2B3B4B5B6B7B8 d12 = B9B10B11B12B13B14B15B16
     vzip.8              d9, d13                                        @ d9 = A1A2A3A4A5A6A7A8 d13 = A9A10A11A12A13A14A15A16
-    vst4.8              {q3, q4}, [\dst,:128]!
-    vst4.8              {q5, q6}, [\dst,:128]!
+    vst4.8              {q3, q4}, [\dst]!
+    vst4.8              {q5, q6}, [\dst]!
 .endm
 
 .macro process_1l_internal dst src ofmt