spi: pxa2xx: limit reaches -1

On line 944 the return value of flush() is considered as a boolean,
but limit reaches -1 upon timeout which evaluates to true.

On 540, 594, 720 the same occurs for wait_ssp_rx_stall()
On 536 the same occurs for wait_dma_channel_stop()

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Eric Miao <eric.miao@marvell.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/pxa2xx_spi.c

@@ -213,7 +213,7 @@ static int flush(struct driver_data *drv_data)
 		while (read_SSSR(reg) & SSSR_RNE) {
 			read_SSDR(reg);
 		}
-	} while ((read_SSSR(reg) & SSSR_BSY) && limit--);
+	} while ((read_SSSR(reg) & SSSR_BSY) && --limit);
 	write_SSSR(SSSR_ROR, reg);
 
 	return limit;
@@ -484,7 +484,7 @@ static int wait_ssp_rx_stall(void const __iomem *ioaddr)
 {
 	unsigned long limit = loops_per_jiffy << 1;
 
-	while ((read_SSSR(ioaddr) & SSSR_BSY) && limit--)
+	while ((read_SSSR(ioaddr) & SSSR_BSY) && --limit)
 		cpu_relax();
 
 	return limit;
@@ -494,7 +494,7 @@ static int wait_dma_channel_stop(int channel)
 {
 	unsigned long limit = loops_per_jiffy << 1;
 
-	while (!(DCSR(channel) & DCSR_STOPSTATE) && limit--)
+	while (!(DCSR(channel) & DCSR_STOPSTATE) && --limit)
 		cpu_relax();
 
 	return limit;