Update arduino_portenta_h7_m7.conf to enable memc

resolves: arduino#74

needed to add: CONFIG_MEMC=y
to have the SDRAM enabled and as such not fault if you do anything with the SDRAM library.
Also enabled CONFIG_DMA=y
As not sure if that was needed but is in the GIGA .conf file

Update arduino_portenta_h7_m7.overlay

Add dma sections to remove the build warnings

Author: KurtE

loader/boards/arduino_portenta_h7_m7.conf

@@ -26,6 +26,8 @@ CONFIG_LLEXT_HEAP_SIZE=128
 
 #CONFIG_ADC=y
 #CONFIG_PWM=y
+CONFIG_DMA=y
+CONFIG_MEMC=y
 CONFIG_SPI_ASYNC=y
 CONFIG_SPI_STM32_INTERRUPT=y
 

loader/boards/arduino_portenta_h7_m7.overlay

@@ -40,6 +40,14 @@
 	pinctrl-names = "default";
 };
 
+&dmamux1 {
+	status = "okay";
+};
+
+&dma1 {
+	status = "okay";
+};
+
 &rng {
 	status = "okay";
 };