video: xilinxfb: Fix compilation warning

regs_phys is phys_addr_t (u32 or u64).
Lets use %pa printk format specifier.

Fixes compilation warning introduced by:
video: xilinxfb: Use drvdata->regs_phys instead of physaddr
(sha1: c88fafef)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>