[IA64-SGI] cpe interrupts are not being enabled.

acpi_request_vector() is called in ia64_mca_init() to get the cpe_vector.
The problem is that acpi_request_vector() looks in platform_intr_list[] to 
get the vector, but platform_intr_list[] is not initialized with a valid
vector until later (in sn_setup()).  Without a valid vector the code
defaults to polling mode.

This patch moves the call to acpi_request_vector() from ia64_mca_init()
to ia64_mca_late_init(), which is after platform_intr_list[] is initialized.

Signed-off-by: Russ Anderson <(rja@sgi.com)>
Signed-off-by: Tony Luck <tony.luck@intel.com>