drm/amdgpu/gfx10: Fix missing break in switch statement

Add missing break statement in order to prevent the code from falling
through to case AMDGPU_IRQ_STATE_ENABLE.

This bug was found thanks to the ongoing efforts to enable
-Wimplicit-fallthrough.

Fixes: a644d85a ("drm/amdgpu: add gfx v10 implementation (v10)")
Cc: stable@vger.kernel.org
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c

@@ -4611,6 +4611,7 @@ gfx_v10_0_set_gfx_eop_interrupt_state(struct amdgpu_device *adev,
 		cp_int_cntl = REG_SET_FIELD(cp_int_cntl, CP_INT_CNTL_RING0,
 					    TIME_STAMP_INT_ENABLE, 0);
 		WREG32(cp_int_cntl_reg, cp_int_cntl);
+		break;
 	case AMDGPU_IRQ_STATE_ENABLE:
 		cp_int_cntl = RREG32(cp_int_cntl_reg);
 		cp_int_cntl = REG_SET_FIELD(cp_int_cntl, CP_INT_CNTL_RING0,