drm/i915/vbt: Rename BDB_LVDS_POWER to BDB_LFP_POWER

Renaming to match the BSpec and struct name.

BSpec: 20150
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200110235045.176640-1-jose.souza@intel.com