update for mbed-os-5.11 (and Nboard IHM-V2)

Dependencies:   IHM_V2

Revision:
28:be81ea276c3a
Parent:
26:0b45eb26bd42
--- a/mbed-os.lib	Sat Feb 10 20:57:06 2018 +0000
+++ b/mbed-os.lib	Wed Jan 09 12:26:00 2019 +0000
@@ -1,1 +1,1 @@
-https://github.com/ARMmbed/mbed-os/#bcf7085d85b2811b5d68bdda192c754eadfb8f88
+https://github.com/ARMmbed/mbed-os/#c966348d3f9ca80843be7cdc9b748f06ea73ced0