My books are packed up and I'm using my phone to post so I don't feel like looking it up so I'll ask if it says that they are proficient with hammers or warhammers. If it says hammers, then yes. If it specifically says warhammer, then no.
However, given dwarves' closeness to smithing, I don't think it would be unreasonable to houserule light hammers into dwarven racial weapon proficiency.