dmaengine: pl08x: Use kcalloc() instead of kzalloc()

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because the "channels"
member can only be 8 or 2. This value is set when the "vendor_data"
structs are initialized.

static struct vendor_data vendor_pl080 = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_nomadik = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_pl080s = {
[...]
.channels = 8,
[...]
};

static struct vendor_data vendor_pl081 = {
[...]
.channels = 2,
[...]
};

However, using kcalloc() is more appropriate [1] and improves
readability. This patch has no effect on runtime behavior.

Link: https://github.com/KSPP/linux/issues/162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Erick Archer <erick.archer@outlook.com>
Link: https://lore.kernel.org/r/AS8PR02MB72373D9261B3B166048A8E218B392@AS8PR02MB7237.eurprd02.prod.outlook.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>