PCI: keystone: Use kcalloc() instead of kzalloc()

Replace calls of devm_kzalloc() with devm_kcalloc() in ks_pcie_probe().
As noted in the kernel documentation [1], open-coded multiplication in
allocator arguments is discouraged because it can lead to integer
overflow.

Using devm_kcalloc() provides built-in overflow protection, making the
memory allocation safer when calculating the allocation size compared
to explicit multiplication.

[1]: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments



Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Link: https://patch.msgid.link/20250819131235.152967-1-rongqianfeng@vivo.com