[Doc] Remove 'Modem Firmware Update' link in service APIs page
[Doc] Remove 'Modem Firmware Update' link in service APIs page

The link of "Modem Firmware Update" in "Service APIs"
(doc/user/html/legatoServices.html) page is to be removed,since the link
already exists in the "Update"(html/legatoServicesUpdateMain.html) page.

Resolves: LE-6729
Change-Id: I6217c6211e6039a51e7c0beea570101d8eee564d

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af