Blackfin: debug-mmrs: disable PERIPHERAL_MAP for IMDMA channels

The documentation for the IMDMA channels appears to be incorrect.
These DMA blocks don't actually have PERIPHERAL_MAP MMRs for us
to access.  Attempts to do so lead to system mmr hardware errors.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/debug-mmrs.c

@@ -223,7 +223,8 @@ bfin_debug_mmrs_dma(struct dentry *parent, unsigned long base, int num, char mdm
 	__DMA(CURR_DESC_PTR, curr_desc_ptr);
 	__DMA(CURR_ADDR, curr_addr);
 	__DMA(IRQ_STATUS, irq_status);
-	__DMA(PERIPHERAL_MAP, peripheral_map);
+	if (strcmp(pfx, "IMDMA") != 0)
+		__DMA(PERIPHERAL_MAP, peripheral_map);
 	__DMA(CURR_X_COUNT, curr_x_count);
 	__DMA(CURR_Y_COUNT, curr_y_count);
 }