remoteproc/mediatek: Remove non-standard dsb()

As reported by Stephen, dsb() is not declared on e.g. x86_64, preventing
the mtp_scp from building. Simply remove the barrier (and the readback),
suggested by Pi-Hsun to resolve this.

Fixes: fd0b6c1f ("remoteproc/mediatek: Add support for mt8192 SCP")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: Pi-Hsun Shih <pihsun@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/mtk_scp.c

@@ -323,10 +323,6 @@ static int mt8192_scp_before_load(struct mtk_scp *scp)
 
 	writel(1, scp->reg_base + MT8192_CORE0_SW_RSTN_SET);
 
-	dsb(sy);
-
-	readl(scp->reg_base + MT8192_CORE0_SW_RSTN_SET);
-
 	/* enable SRAM clock */
 	mt8192_power_on_sram(scp->reg_base + MT8192_L2TCM_SRAM_PD_0);
 	mt8192_power_on_sram(scp->reg_base + MT8192_L2TCM_SRAM_PD_1);