LoongArch: Don't panic if no valid cache info for PCI

LoongArch: Don't panic if no valid cache info for PCI

commit a6b533adfc05ba15360631e019d3e18275080275 upstream.

If there is no valid cache info detected (may happen in virtual machine)
for pci_dfl_cache_line_size, kernel shouldn't panic. Because in the PCI
core it will be evaluated to (L1_CACHE_BYTES >> 2).

Cc: <stable@vger.kernel.org>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>