net/faraday: Explicitly include linux/of.h and linux/property.h

This driver uses interfaces from linux/of.h and linux/property.h but
relies on implict inclusion of those headers which means that changes in
other headers could break the build, as happened in -next for arm today.
Add a explicit includes.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>