pldmbios: Add BIOS attributes huge_page_count lmb_size mfg_flags

Hostboot reads hb_requested_number_huge_pages and sets
ATTR_HUGE_PAGE_COUNT, reads hb_pending_memory_region_size and
sets ATTR_LMB_SIZE, reads hb_mfg_flags and sets ATTR_MFG_FLAGS.
Tested: manually added bios attrs in rainier simics and
successfully read from hostboot.

Signed-off-by: Corey Swenson <cswenson@us.ibm.com>
Change-Id: Idfef7fd97b16d7cbf1bf72764387535e200c78e0