Remove superflous apt-get update from .travis.yml

.travis.yml

@@ -1,8 +1,6 @@
 language: c
 
 before_install:
-    - sudo apt-get update
-
     - sudo apt-get install emdebian-archive-keyring
     - echo 'deb http://www.emdebian.org/debian wheezy main' | sudo tee /etc/apt/sources.list.d/emdebian.list > /dev/null
 
@@ -10,8 +8,6 @@ before_install:
     - echo 'deb http://us.archive.ubuntu.com/ubuntu trusty-backports main restricted universe multiverse' | sudo tee -a /etc/apt/sources.list.d/trusty.list > /dev/null
     - echo 'deb http://us.archive.ubuntu.com/ubuntu trusty-security  main restricted universe multiverse' | sudo tee -a /etc/apt/sources.list.d/trusty.list > /dev/null
     - echo 'deb http://us.archive.ubuntu.com/ubuntu trusty-updates   main restricted universe multiverse' | sudo tee -a /etc/apt/sources.list.d/trusty.list > /dev/null
-    - sudo apt-get update
-
     - sudo add-apt-repository -y ppa:terry.guo/gcc-arm-embedded
     - sudo apt-get update