x86, UV: Fix information in __uv_hub_info structure

A few parts of the uv_hub_info structure are initialized
incorrectly.

 - n_val is being loaded with m_val.
 - gpa_mask is initialized with a bytes instead of an unsigned long.
 - Handle the case where none of the alias registers are used.

Lastly I converted the bau over to using the uv_hub_info->m_val
which is the correct value.

Without this patch, booting a large configuration hits a
problem where the upper bits of the gnode affect the pnode
and the bau will not operate.

Signed-off-by: Robin Holt <holt@sgi.com>
Acked-by: Jack Steiner <steiner@sgi.com>
Cc: Cliff Whickman <cpw@sgi.com>
Cc: stable@kernel.org
LKML-Reference: <20091015224946.396355000@alcatraz.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>