spi: zynq-qspi: Adjust xqspips_init_hw() prototype

Instead of xqspips_init_hw(xqspi->regs, xqspi->is_dual),
simply call xqspips_init_hw(xqspi), aligning this functions with others.
[The old prototype may have been necessary in previous version
of the driver, but it isn't any longer.]

Signed-off-by: Thomas Betker <thomas.betker@rohde-schwarz.com>
Reviewed-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>