IB/qib: Drop qib_tune_pcie_caps() and qib_tune_pcie_coalesce() return values

The callers of qib_tune_pcie_caps() and qib_tune_pcie_coalesce() don't
check the return values, so this patch drops the return values altogether.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Mike Marciniszyn <mike.marciniszyn@intel.com>