PCI/sysfs: Add CAP_SYS_ADMIN check to __resource_resize_store()

PCI/sysfs: Add CAP_SYS_ADMIN check to __resource_resize_store()

Currently, the __resource_resize_store() allows writing to the
resourceN_resize sysfs attribute to change a BAR's size without checking
for capabilities, currently relying only on the file access check.

Resizing a BAR modifies PCI device configuration and can disrupt active
drivers.  After the upcoming conversion to static attributes, it will also
trigger resource file updates via sysfs_update_groups().

Add a CAP_SYS_ADMIN check to prevent unprivileged users from performing BAR
resize operations.

Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20260508043543.217179-6-kwilczynski@kernel.org