Fix bad overflow check in hw/pci/pcie.c

Fix bad overflow check in hw/pci/pcie.c

Orginal qemu commit hash:14d02cfbe4adaeebe7cb833a8cc71191352cf03b

In function pcie_add_capability, an assert contains the
"offset < offset + size" expression.
Both variable offset and variable size are uint16_t,
the comparison is always true due to type promotion.
The next expression may be the same.

It might be like this:
Thread 1 "qemu-system-x86" hit Breakpoint 1, pcie_add_capability (
    dev=0x555557ce5f10, cap_id=1, cap_ver=2 '\002', offset=256, size=72)
    at ../hw/pci/pcie.c:930
930	{
(gdb) n
931	    assert(offset >= PCI_CONFIG_SPACE_SIZE);
(gdb) n
932	    assert(offset < offset + size);
(gdb) p offset
$1 = 256
(gdb) p offset < offset + size
$2 = 1
(gdb) set offset=65533
(gdb) p offset < offset + size
$3 = 1
(gdb) p offset < (uint16_t)(offset + size)
$4 = 0

Signed-off-by: Daniella Lee <daniellalee111@gmail.com>
Message-Id: <20211126061324.47331-1-daniellalee111@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>