Arduino_LED_Matrix: add const to matrixWrite #774

Job	Run time
Build and package cores	9m 45s
Split off zephyr	9s
Split off zephyr_main	13s
Split off zephyr_contrib	6s
Split off zephyr_unoq	6s
Test zephyr_main:nano33ble	1m 53s
Test zephyr_main:portentac33	2m 39s
Test zephyr_main:niclasense	2m 27s
Test zephyr_main:giga	2m 30s
Test zephyr_contrib:ek_ra8d1	1m 56s
Test zephyr_main:portentah7	2m 13s
Test zephyr_contrib:frdm_mcxn947	2m 29s
Test zephyr_main:opta	2m 31s
Test zephyr_contrib:frdm_rw612	2m 22s
Test zephyr:unoq	1m 50s
Publish jsons	19s
Collect logs	6s
verify-core	-1s
Publish core	-1s
cleanup-artifacts	5s
	33m 37s

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