i2c: i2c_xilinx_axi: Fix armclang compile warning

Use PRIxPTR macros to fix compiler warnings of the form:

i2c_xilinx_axi.c:266:50: warning: format specifies type 'unsigned long'
but the argument has type 'mem_addr_t' (aka 'unsigned int') [-Wformat]
        LOG_INF("Configuring %s at 0x%08lx", dev->name, config->base);
                                     ~~~~~              ^~~~~~~~~~~~
                                     %08x

Signed-off-by: Kumar Gala <kumar.gala@intel.com>