sparc32: off by ones in BUG_ON()

Smatch complains that these tests are off by one, which is true but not
life threatening.

	arch/sparc/kernel/irq_32.c:169 irq_link()
	error: buffer overflow 'irq_map' 384 <= 384

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>