arch/sparc: Fix indexing msi_msiqid_table and msi_irq_table

arch/sparc: Fix indexing msi_msiqid_table and msi_irq_table

Orabug: 25391918

Couple of indexing fixes.
1. Fix indexing pbm->msi_msiqid_table. It is initialized
   based off of pbm->msi_first(not pbm->msiq_first as previously done).
   Here is how it is initialized(Look at in sparc64_setup_msi_irq)
   pbm->msi_msiqid_table[msi - pbm->msi_first] = msiqid;

2. In set_related_affinity, we dont need to subtract msi_first as
   the loop is indexed from 0 to size of the table.

(cherry picked from uek2 commit 57d31847c9f2011314de8ea98c06616f91c5dbb8)

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Tested-by: Dmitry Klochkov <dmitry.klochkov@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>