net: wwan: iosm: use int type to store negative error codes

net: wwan: iosm: use int type to store negative error codes

The 'ret' variable in ipc_pcie_resources_request() either stores '-EBUSY'
directly or holds returns from pci_request_regions() and ipc_acquire_irq().
Storing negative error codes in u32 causes no runtime issues but is
stylistically inconsistent and very ugly.  Change 'ret' from u32 to int
type - this has no runtime impact.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Link: https://patch.msgid.link/20250826135021.510767-1-rongqianfeng@vivo.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>