flashbench: use lower number of samples in -a test

Turns out a bit too much, and might hide some effects.
Also, using something just below a power of two works
better, so use 7 now.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/flashbench.c b/flashbench.c
index a31e479..60980d7 100644
--- a/flashbench.c
+++ b/flashbench.c
@@ -322,7 +322,7 @@
 
 static int try_read_alignments(struct device *dev, int tries, int blocksize)
 {
-	const int count = 32;
+	const int count = 7;
 	int ret;
 	off_t align, maxalign;