PCI: brcmstb: Fix build on 32bit ARM platforms with older compilers

commit 73a7a27 upstream.

Some older compilers have no implementation for the helper for 64-bit
unsigned division/modulo, so linking pcie-brcmstb driver causes the
"undefined reference to `__aeabi_uldivmod'" error.

*rc_bar2_size is always a power of two, because it is calculated as:
"1ULL << fls64(entry->res->end - entry->res->start)", so the modulo
operation in the subsequent check can be replaced by a simple logical
AND with a proper mask.

Link: https://lore.kernel.org/r/20200227115146.24515-1-m.szyprowski@samsung.com
Fixes: c045213 ("PCI: brcmstb: Add Broadcom STB PCIe host controller driver")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/pcie-brcmstb.c

@@ -670,7 +670,7 @@ static inline int brcm_pcie_get_rc_bar2_size_and_offset(struct brcm_pcie *pcie,
 	 *   outbound memory @ 3GB). So instead it will  start at the 1x
 	 *   multiple of its size
 	 */
-	if (!*rc_bar2_size || *rc_bar2_offset % *rc_bar2_size ||
+	if (!*rc_bar2_size || (*rc_bar2_offset & (*rc_bar2_size - 1)) ||
 	    (*rc_bar2_offset < SZ_4G && *rc_bar2_offset > SZ_2G)) {
 		dev_err(dev, "Invalid rc_bar2_offset/size: size 0x%llx, off 0x%llx\n",
 			*rc_bar2_size, *rc_bar2_offset);