From the description of the Necromancy school in the basic rules v1 (emphasis mine)

Necromancy spells manipulate the energies of life and death. Such spells can grant an extra reserve of life force, drain the life energy from another creature, create the undead, or even bring the dead back to life. Creating the undead through the use of necromancy spells such as animate dead is not a good act, and only evil casters use such spells frequently.

It seems like you can assume necromancy is evil unless a usually good spellcaster uses it infrequently. The key is in the "frequently". I think it's up to your GM to say if animating deads once a day is considered frequent enough to make you evil.

Generalizing about necromancy is a matter of survival for common folks. The crazy dude in town digging graves and experimenting with corpses is not necessarily evil, but you'd be a fool to assume he's not. In almost all the settings I know (I'm not the most literate about FR but I've never read anything about a good necromancer) necromancy is either straight evil or shady...really shady. Unless NPCs have affiliations or knowledge of the contrary, they will be suspicious of necromancers.

With the release of Mordenkainen's Tome of Foes, there is a list on page 73 of dwarven deities and their domains. Berronar Truesilver and Tharmekhûl both have the Light domain. I'll leave my original answer below the break for reference in case future readers wouldn't prefer the two deities listed above.

Dugmaren Brightmantle seems like a good candidate. From the Wikipedia page:

Dugmaren Brightmantle is the dwarf deity of scholarship, discovery, and invention. Dugmaren shares the Dwarven Mountain on the Outlands with Dumathoin and Vergadain. Dugmaren appears as an elderly dwarf with sparkling blue eyes.

His domain isn't strictly light, but those domains are probably more of a suggestion. It could be argued that Light would be a fitting domain for this deity. Discovery, knowledge, and enlightenment go hand-in-hand with light in certain deity systems. Alternatively, Marthammor Duin could be an option since that deity has an affinity for lightning.

Tharmekhûl could be an option as well due to being associated with fire and the light domain has quite a few fire spells.

Source: Dwarf Deities on Wikipedia