dt-bindings: vendor-prefixes: add HPE Prefix

Description: This patch adds the Hewlett Packard Enterprise prefix
that will be used for upcoming support in the HPE BMC GXP.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220210175912.102159-1-nick.hawkins@hpe.com