Blackfin: no-mpu: fix masking of small uncached dma region

When using an uncached DMA region less than 1 MiB, we try to mask off
the whole last 1 MiB for it.  Unfortunately, this fails as we forgot
to subtract one from the calculated mask, leading to the region still
be marked as cacheable.
Reported-by: Andrew Rook <andrew.rook@speakerbus.co.uk>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/cplb-nompu/cplbinit.c

@@ -116,7 +116,7 @@ void __init generate_cplb_tables_all(void)
 	    ((_ramend - uncached_end) >= 1 * 1024 * 1024))
 		dcplb_bounds[i_d].eaddr = uncached_end;
 	else
-		dcplb_bounds[i_d].eaddr = uncached_end & ~(1 * 1024 * 1024);
+		dcplb_bounds[i_d].eaddr = uncached_end & ~(1 * 1024 * 1024 - 1);
 	dcplb_bounds[i_d++].data = SDRAM_DGENERIC;
 	/* DMA uncached region.  */
 	if (DMA_UNCACHED_REGION) {