lavc/pixblockdsp: add scalar get_pixels_unaligned

The code is already there, we just need to use it.

get_pixels_unaligned_c: 2.2
get_pixels_unaligned_misaligned: 1.7

libavcodec/riscv/pixblockdsp_init.c

@@ -55,6 +55,13 @@ av_cold void ff_pixblockdsp_init_riscv(PixblockDSPContext *c,
             c->get_pixels = ff_get_pixels_8_rvi;
     }
 
+    if (cpu_flags & AV_CPU_FLAG_RV_MISALIGNED) {
+        if (high_bit_depth)
+            c->get_pixels_unaligned = ff_get_pixels_16_rvi;
+        else
+            c->get_pixels_unaligned = ff_get_pixels_8_rvi;
+    }
+
 #if HAVE_RVV
     if ((cpu_flags & AV_CPU_FLAG_RVV_I32) && ff_rv_vlen_least(128)) {
         c->diff_pixels = ff_diff_pixels_unaligned_rvv;