spi: xilinx: Fix info message during probe

The info message was showing the mapped address of the device. To avoid
security problems, all virtual addresses are converted to __ptrval__, so
the message was useless/ugly:

[    2.304949] xilinx_spi b0010000.spi-flash: at 0xB0010000 mapped to 0x(____ptrval____), irq=37

Use %pR instead:

[   15.021354] xilinx_spi b0010000.spi-flash: at [mem 0xb0010000-0xb001ffff], irq=37

Signed-off-by: Ricardo Ribalda <ribalda@kernel.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/20200915112936.320647-1-ribalda@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>