regulator: bd71837: Remove duplicate description from DT bindings

Same general chip description was written in MFD and Regulator
binding documents for ROHM bd71837 PMIC. Remove description from
regulator binding as suggested by Rob H.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.txt

 ROHM BD71837 Power Management Integrated Circuit (PMIC) regulator bindings
 
-BD71837MWV is a programmable Power Management
-IC (PMIC) for powering single-core, dual-core, and
-quad-core SoC’s such as NXP-i.MX 8M. It is optimized
-for low BOM cost and compact solution footprint. It
-integrates 8 Buck regulators and 7 LDO’s to provide all
-the power rails required by the SoC and the commonly
-used peripherals.
-
 Required properties:
  - regulator-name: should be "buck1", ..., "buck8" and "ldo1", ..., "ldo7"