ARM64: zynqmp: Sync zynq_sdhci_init() declaration

This patch fix compilation error:
drivers/mmc/zynq_sdhci.c:16:5: error: conflicting types for
‘zynq_sdhci_init’
 int zynq_sdhci_init(phys_addr_t regbase)
     ^
In file included from drivers/mmc/zynq_sdhci.c:14:0:
./arch/arm/include/asm/arch/sys_proto.h:16:5: note: previous declaration
of ‘zynq_sdhci_init’ was here
 int zynq_sdhci_init(unsigned long regbase);
     ^

Signed-off-by: Michal Simek <michal.simek@xilinx.com>