boards: portentah7: Fix partition size #750

Job	Run time
Build and package cores	9m 59s
Split off zephyr_main	17s
Split off zephyr_contrib	8s
Split off zephyr	14s
Split off zephyr_unoq	6s
Test zephyr_main:niclasense	2m 27s
Test zephyr_main:giga	2m 31s
Test zephyr_main:nano33ble	2m 35s
Test zephyr_main:portentac33	2m 29s
Test zephyr:unoq	2m 25s
Test zephyr_main:portentah7	2m 36s
Test zephyr_main:opta	2m 25s
Test zephyr_contrib:frdm_rw612	2m 26s
Test zephyr_contrib:frdm_mcxn947	2m 17s
Test zephyr_contrib:ek_ra8d1	2m 30s
Collect logs	1m 7s
Publish jsons	22s
Publish core	0s
verify-core	0s
cleanup-artifacts	6s
	37m 0s

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