MAINTAINERS: add myself as reviewer of i.MX8M related patches

I wrote the i.MX8M platform and UART support and can help review
patches touching these areas.

Signed-off-by: Wig Cheng <onlywig@gmail.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

MAINTAINERS

@@ -365,6 +365,13 @@ F:	tools/misc/xenhypfs.c
 F:	xen/common/hypfs.c
 F:	xen/include/xen/hypfs.h
 
+IMX8M SUPPORT
+R:	Wig Cheng <onlywig@gmail.com>
+F:	xen/arch/arm/arm64/debug-imx-uart.inc
+F:	xen/arch/arm/include/asm/imx-uart.h
+F:	xen/arch/arm/platforms/imx8m.c
+F:	xen/drivers/char/imx-uart.c
+
 IMX8QM/QXP SUPPORT
 R:	John Ernberg <john.ernberg@actia.se>
 F:	xen/arch/arm/platforms/imx8qm.c

xen/arch/arm/platforms/imx8m.c

@@ -111,14 +111,8 @@ static bool imx8m_smc(struct cpu_user_regs *regs)
          * NoC QoS priority setup.  Only i.MX8MQ issues this at boot;
          * i.MX8MP issues no NoC call, but the platform covers both.
          */
-        switch ( subfunction_id )
-        {
-        case IMX_SIP_NOC_SF_PRIORITY:
-            break;
-
-        default:
+        if ( subfunction_id != IMX_SIP_NOC_SF_PRIORITY )
             return false;
-        }
         break;
 
     default: