misc: pci_endpoint_test: Handle BAR sizes larger than INT_MAX

Running 'pcitest -b 0' fails with "TEST FAILED" when the BAR0 size
is e.g. 8 GB.

The return value of the pci_resource_len() macro can be larger than that
of a signed integer type. Thus, when using 'pcitest' with an 8 GB BAR,
the bar_size of the integer type will overflow.

Change bar_size from integer to resource_size_t to prevent integer
overflow for large BAR sizes with 32-bit compilers.

In order to handle 64-bit resource_type_t on 32-bit platforms, we would
have needed to use a function like div_u64() or similar. Instead, change
the code to use addition instead of division. This avoids the need for
div_u64() or similar, while also simplifying the code.

Fixes: cda370ec ("misc: pci_endpoint_test: Avoid using hard-coded BAR sizes")
Co-developed-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250124093300.3629624-2-cassel@kernel.org


[mani: added fixes tag]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>