UBUNTU: SAUCE: snapcraft: cleanup and remove unnecessary elements

1) the branch name is only useful when distributing the snapcraft.yaml alone -
when it is part of a git tree, the branch name should be omitted if the
intention is to snap the branch containing the snapcraft.yaml file itself

2) SQUASHFs is not a separate module anymore (see
da89f0b2)

3) d101m_ucode.bin, d101s_ucode.bin and d102e_ucode.bin are only necessary when
using an Intel(R) PRO/100 nic, while the main amd64 target is kvm (and that uses
an Intel e1000 firmware-less nic)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

snapcraft.yaml

@@ -8,16 +8,9 @@ parts:
   kernel:
     plugin: kernel
     source: .
-    source-branch: master
     source-type: git
     kdefconfig: ['--makefile=debian/snapcraft.mk', 'branch=master','flavour=generic', 'config']
     kconfigs:
       - CONFIG_LOCALVERSION="-xenial_generic"
       - CONFIG_DEBUG_INFO=n
-    kernel-initrd-modules:
-      - squashfs
-    kernel-initrd-firmware:
-      - lib/firmware/e100/d101m_ucode.bin
-      - lib/firmware/e100/d101s_ucode.bin
-      - lib/firmware/e100/d102e_ucode.bin
     kernel-image-target: bzImage