Mailbox_From_SDM Address Map

Door Bell registers to allow RW by both SDM and external masters

Module Instance	Base Address	End Address
`i_mailbox_fromsdm`	`0xFFA30480`	`0xFFA3048B`

Register	Offset	Width	Access	Reset Value	Description
`sdm2em`	`0x0`	`32`	`RW`	`0x00000000`	SDM to External Master doorbell register