services/mgmt/device/impl/profile.go: use linux-386 rather than linux-x86

Change the profile name used for 32-bit x86 binaries to be linux-386 rather
than linux-x86 to be consistent with GOARCH=386 (which puts binaries in
bin/linux_386). The earlier discrepancy made it painful to use device publish
to push binaries.

Change-Id: I44943b8fd586d0c319ec66149e5b2ccd3a2a0633
diff --git a/services/mgmt/device/impl/profile.go b/services/mgmt/device/impl/profile.go
index 8b86817..f21cdb3 100644
--- a/services/mgmt/device/impl/profile.go
+++ b/services/mgmt/device/impl/profile.go
@@ -156,7 +156,7 @@
 			Format:      build.ELF,
 		},
 		{
-			Label:       "linux-x86",
+			Label:       "linux-386",
 			Description: "",
 			Arch:        build.X86,
 			Os:          build.Linux,