swscale/rgb2rgb: enable R-V V deinterleaveBytes

T-Head C908:
deinterleave_bytes_c:                               100328.3 ( 1.00x)
deinterleave_bytes_rvv_i32:                          19331.3 ( 5.19x)
deinterleave_bytes_aligned_c:                       100337.5 ( 1.00x)
deinterleave_bytes_aligned_rvv_i32:                  15748.0 ( 6.37x)

SpacemiT X60:
deinterleave_bytes_c:                                95230.6 ( 1.00x)
deinterleave_bytes_rvv_i32:                           9790.3 ( 9.73x)
deinterleave_bytes_aligned_c:                        96564.1 ( 1.00x)
deinterleave_bytes_aligned_rvv_i32:                   7780.1 (12.41x)

libswscale/riscv/rgb2rgb.c

@@ -33,6 +33,9 @@ void ff_shuffle_bytes_3210_rvb(const uint8_t *src, uint8_t *dst, int src_len);
 void ff_interleave_bytes_rvv(const uint8_t *src1, const uint8_t *src2,
                              uint8_t *dst, int width, int height, int s1stride,
                              int s2stride, int dstride);
+void ff_deinterleave_bytes_rvv(const uint8_t *src, uint8_t *dst1,
+                               uint8_t *dst2, int width, int height,
+                               int srcStride, int dst1Stride, int dst2Stride);
 void ff_uyvytoyuv422_rvv(uint8_t *ydst, uint8_t *udst, uint8_t *vdst,
                          const uint8_t *src, int width, int height,
                          int ystride, int uvstride, int src_stride);
@@ -56,6 +59,7 @@ av_cold void rgb2rgb_init_riscv(void)
         shuffle_bytes_1230 = ff_shuffle_bytes_1230_rvv;
         shuffle_bytes_3012 = ff_shuffle_bytes_3012_rvv;
         interleaveBytes = ff_interleave_bytes_rvv;
+        deinterleaveBytes = ff_deinterleave_bytes_rvv;
         uyvytoyuv422 = ff_uyvytoyuv422_rvv;
         yuyvtoyuv422 = ff_yuyvtoyuv422_rvv;
     }