arm/aarch64: vp9itxfm: Skip loading the min_eob pointer when it won't be used

In the half/quarter cases where we don't use the min_eob array, defer
loading the pointer until we know it will be needed.

This is cherrypicked from libav commit
3a0d5e20.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/aarch64/vp9itxfm_neon.S

@@ -1483,7 +1483,6 @@ function ff_vp9_idct_idct_32x32_add_neon, export=1
         b.eq            idct32x32_dc_add_neon
 
         movrel          x10, idct_coeffs
-        movrel          x12, min_eob_idct_idct_32, 2
 
         mov             x15, x30
 
@@ -1508,6 +1507,8 @@ function ff_vp9_idct_idct_32x32_add_neon, export=1
         cmp             w3,  #135
         b.le            idct32x32_half_add_neon
 
+        movrel          x12, min_eob_idct_idct_32, 2
+
 .irp i, 0, 8, 16, 24
         add             x0,  sp,  #(\i*64)
 .if \i > 0

libavcodec/arm/vp9itxfm_neon.S

@@ -889,8 +889,6 @@ function ff_vp9_\txfm1\()_\txfm2\()_16x16_add_neon, export=1
         push            {r4-r8,lr}
 .ifnc \txfm1\()_\txfm2,idct_idct
         vpush           {q4-q7}
-.else
-        movrel          r8,  min_eob_idct_idct_16 + 2
 .endif
 
         @ Align the stack, allocate a temp buffer
@@ -914,6 +912,8 @@ A       and             r7,  sp,  #15
         ble             idct16x16_quarter_add_neon
         cmp             r3,  #38
         ble             idct16x16_half_add_neon
+
+        movrel          r8,  min_eob_idct_idct_16 + 2
 .endif
 
 .irp i, 0, 4, 8, 12