Change in coreboot[master]: drivers/smmstore: Expose region device

[Angel Pons (Code Review)]

Attention is currently required from: Patrick Rudolph.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62014 )

Change subject: drivers/smmstore: Expose region device
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Patch Set 4: Code-Review+1

(1 comment)

File src/drivers/smmstore/store.c:

https://review.coreboot.org/c/coreboot/+/62014/comment/4dca2671_1bb2bb30 
PS4, Line 103: ret = CB_ERR;
             : 		} else {
             : 			ret = CB_SUCCESS;
As the other functions in this file return 0 or -1, maybe do the same here for consistency?