utils: Add partition concatenation routine.

Follow kernel convention and add 'p' if the block device ends with a digit.
Fixes platform_PartitionCheck test.
Follow same method for faft test.

BUG=chromium:776029
TEST=unit test, test latform_PartitionCheck on NVMe.

Change-Id: I61f2f194e149634e132a4ad548335ea7c10d8366
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/741483
Reviewed-by: Sridhar Sonti <sontis@google.com>
Reviewed-by: Wai-Hong Tam <waihong@google.com>
diff --git a/client/bin/utils.py b/client/bin/utils.py
index 79b4d15..a60b658 100644
--- a/client/bin/utils.py
+++ b/client/bin/utils.py
@@ -910,6 +910,20 @@
     # For harddisk rtt > 0
     return rtt and int(rtt) > 0
 
+def concat_partition(disk_name, partition_number):
+    """
+    Return the name of a partition:
+    sda, 3 --> sda3
+    mmcblk0, 3 --> mmcblk0p3
+
+    @param disk_name: diskname string
+    @param partition_number: integer
+    """
+    if disk_name.endswith(tuple(str(i) for i in range(0, 10))):
+        sep = 'p'
+    else:
+        sep = ''
+    return disk_name + sep + str(partition_number)
 
 def verify_hdparm_feature(disk_name, feature):
     """