MIPS: ath25: Check for kzalloc allocation failure

Currently there is no null check on a failed allocation of board_data,
and hence a null pointer dereference will occurr. Fix this by checking
for the out of memory null pointer.

Fixes: a7473717 ("MIPS: ath25: add board configuration detection")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.19+
Patchwork: https://patchwork.linux-mips.org/patch/18657/Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/ath25/board.c

@@ -135,6 +135,8 @@ int __init ath25_find_config(phys_addr_t base, unsigned long size)
 	}
 
 	board_data = kzalloc(BOARD_CONFIG_BUFSZ, GFP_KERNEL);
+	if (!board_data)
+		goto error;
 	ath25_board.config = (struct ath25_boarddata *)board_data;
 	memcpy_fromio(board_data, bcfg, 0x100);
 	if (broken_boarddata) {