microblaze: Remove DEBUG_INT macro and use debug() instead

Do not use specific macros for debugging.
Also remove compilation warning:
w+../arch/microblaze/cpu/interrupts.c: In function 'interrupt_handler':
w+../arch/microblaze/cpu/interrupts.c:153:2: warning: format '%x'
expects argument of type 'unsigned int', but argument 2 has type 'void
(*)(void *)' [-Wformat]
w+../arch/microblaze/cpu/interrupts.c:153:2: warning: format '%x'
expects argument of type 'unsigned int', but argument 4 has type 'void
*' [-Wformat]

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