usb: host: xhci: mvebu: Iterate over array indexes instead of using pointer math

stable inclusion
from stable-v5.10.173
commit 426cbe9a0a688533eb286e1298bd9e66be7f806f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7X0QU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=426cbe9a0a688533eb286e1298bd9e66be7f806f



--------------------------------

[ Upstream commit 0fbd2cda ]

Walking the dram->cs array was seen as accesses beyond the first array
item by the compiler. Instead, use the array index directly. This allows
for run-time bounds checking under CONFIG_UBSAN_BOUNDS as well. Seen
with GCC 13 with -fstrict-flex-arrays:

In function 'xhci_mvebu_mbus_config',
    inlined from 'xhci_mvebu_mbus_init_quirk' at ../drivers/usb/host/xhci-mvebu.c:66:2:
../drivers/usb/host/xhci-mvebu.c:37:28: warning: array subscript 0 is outside array bounds of 'const struct mbus_dram_window[0]' [-Warray-bounds=]
   37 |                 writel(((cs->size - 1) & 0xffff0000) | (cs->mbus_attr << 8) |
      |                          ~~^~~~~~

Cc: Mathias Nyman <mathias.nyman@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230204183651.never.663-kees@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>