ARM: dts: socfpga: arria10: 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>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
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v2: fix compile error