amdgcn: Fix 64-bit vector multiply

Fix an old maths bug with DImode vector multiply.

Backport from mainline.

gcc/ChangeLog:

	* config/gcn/gcn-valu.md (mul<mode>3): Remove erroneous hi*hi step.
	(mul<mode>3_dup): Likewise.
	(mul<mode>3_exec): Likewise.
	(mul<mode>3_dup_exec): Likewise.

(cherry picked from commit 0a1f6acb90e27ac0b2984ad6841186ca54bc5725)
1 file changed