arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level

In the Linux kernel, the following vulnerability has been resolved:

arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level

Though acpi_find_last_cache_level() always returned signed value and the
document states it will return any errors caused by lack of a PPTT table,
it never returned negative values before.

Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
however changed it by returning -ENOENT if no PPTT was found. The value
returned from acpi_find_last_cache_level() is then assigned to unsigned
fw_level.

It will result in the number of cache leaves calculated incorrectly as
a huge value which will then cause the following warning from __alloc_pages
as the order would be great than MAX_ORDER because of incorrect and huge
cache leaves value.

| WARNING: CPU: 0 PID: 1 at mm/page_alloc.c:5407 __alloc_pages+0x74/0x314
| Modules linked in:
| CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-10393-g7c2a8d3ac4c0 #73
| pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : __alloc_pages+0x74/0x314
| lr : alloc_pages+0xe8/0x318
| Call trace:
| __alloc_pages+0x74/0x314
| alloc_pages+0xe8/0x318
| kmalloc_order_trace+0x68/0x1dc
| __kmalloc+0x240/0x338
| detect_cache_attributes+0xe0/0x56c
| update_siblings_masks+0x38/0x284
| store_cpu_topology+0x78/0x84
| smp_prepare_cpus+0x48/0x134
| kernel_init_freeable+0xc4/0x14c
| kernel_init+0x2c/0x1b4
| ret_from_fork+0x10/0x20

Fix the same by changing fw_level to be signed integer and return the
error from init_cache_level() early in case of error.