fs: Correct errno when not finding a mounted filesystem

[geky]

See #5362

We should be reporting ENODEV when we resolve a path to no filesystem
cc @TeroJaasko, @kjbracey-arm

[0xc0170]

/morph build

[mbed-ci]

Build : FAILURE

Build number : 327
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/5373/

[studavekar]

This is yet another again github pull issue, I guess something has changed form github side.
started seeing this since yesterday.

Receiving objects:  63% (21329/33727), 52.21 MiB | 49.00 KiB/s   
fatal: The remote end hung up unexpectedly
00:20:04.892 fatal: early EOF
00:20:04.892 fatal: index-pack failed
00:20:04.892 
00:20:04.892 	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1924)
00:20:04.892 	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:1643)
00:20:04.892 	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.access$300(CliGitAPIImpl.java:71)
00:20:04.892 	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(CliGitAPIImpl.java:352)

[adbridge]

@studavekar I noticed there were reports of network issues in Austin yesterday so the interaction with github may have been down to that. Will restart.

/morph build

[adbridge]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 387
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/5373/

Triggering tests

/morph test
/morph uvisor-test

[mbed-ci]

Test : SUCCESS

Build number : 187
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/5373/187