tools: PCI: Zero-initialize param

The values in param may be random if they are not initialized, which
may cause use_dma flag set even when "-d" option is not provided
in command line. Initializing all members to 0 to solve this.

Link: https://lore.kernel.org/r/20210714132331.5200-1-yang.shunyong@gmail.com
Signed-off-by: Shunyong Yang <yang.shunyong@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>