arch: riscv: Add -msave-restore option to reduce code footprint #240878

Job	Run time
twister-build-prep	4m 23s
twister-build (3)	27m 37s
twister-build (4)	27m 27s
twister-build (1)	25m 25s
twister-build (8)	19m 14s
twister-build (2)	21m 14s
twister-build (5)	20m 28s
twister-build (6)	31m 50s
twister-build (7)	38m 20s
twister-build (12)	20m 48s
twister-build (10)	18m 38s
twister-build (9)	19m 56s
twister-build (13)	25m 26s
twister-build (11)	22m 51s
Publish Unit Tests Results	1m 20s
Check Twister Status / all jobs passed	4s
	5h 25m 1s

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