PCI / ACPI: Fix build of the AER driver for CONFIG_ACPI unset

After commit 415e12b23792 ("PCI/ACPI: Request _OSC control once for each
root bridge (v3)") include/linux/pci-acpi.h is included by
drivers/pci/pcie/aer/aerdrv.c and if CONFIG_ACPI is unset, the bogus and
unnecessary alternative definition of acpi_find_root_bridge_handle()
causes a build error to occur.

Remove the offending piece of garbage.

Reported-and-tested-by: Stephen Rothwell <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/pci-acpi.h

···
 	return acpi_get_pci_rootbridge_handle(pci_domain_nr(pbus),
 					      pbus->number);
 }
-#else
-static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
-{ return NULL; }
 #endif
 
 #ifdef CONFIG_ACPI_APEI