misc: pci_endpoint_test: Remove redundant 'remainder' test

misc: pci_endpoint_test: Remove redundant 'remainder' test

A BAR size is always a power of two. buf_size = min(SZ_1M, bar_size).
If the BAR size is <= 1MB, there will be one iteration, no remainder.
If the BAR size is > 1MB, there will be more than one iteration, but the
size will always be evenly divisible by 1MB, so no remainder.

Link: https://lore.kernel.org/r/20250109094556.1724663-2-18255117159@163.com
Suggested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>