freedreno/a6xx: fix OUT_REG() vs growable cmdstream

BEGIN_RING() could decide we can't fit the next packet in the current
cmdstream segment, and grow a new segment.  So we need to grab ring->cur
*after* BEGIN_RING(), otherwise we are writing cmdstream past the end of
the previous segment.

Fixes: bdd98b892f ("freedreno: New struct packing macros")
Signed-off-by: Rob Clark <robdclark@chromium.org>

src/gallium/drivers/freedreno/a6xx/fd6_pack.h

@@ -76,12 +76,12 @@ struct fd_reg_pair {
 	do {													\
 		const struct fd_reg_pair regs[] = { __VA_ARGS__ };	\
 		unsigned count = ARRAY_SIZE(regs);					\
-		uint32_t *p = ring->cur;							\
 															\
 		STATIC_ASSERT(count > 0);							\
 		STATIC_ASSERT(count <= 16);							\
 															\
 		BEGIN_RING(ring, count + 1);						\
+		uint32_t *p = ring->cur;							\
 		*p++ = CP_TYPE4_PKT | count |						\
 			(_odd_parity_bit(count) << 7) |					\
 			((regs[0].reg & 0x3ffff) << 8) |				\