atm: iphase: Do PCI error checks on own line

atm: iphase: Do PCI error checks on own line

In get_esi() PCI errors are checked inside line-split "if" conditions (in
addition to the file not following the coding style). To make the code in
get_esi() more readable, fix the coding style and use the usual error
handling pattern with a separate variable.

In addition, initialization of 'error' variable at declaration is not
needed.

No functional changes intended.

Link: https://lore.kernel.org/r/20230911125354.25501-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>