ARM: dts: socfpga: cyclone5: align regulator node with dtschema

Fixes dtbs_check warnings like:

'3-3-v-regulator' does not match any of the regexes: '.*-names$'

Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>:wq
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>