Kernel : Use Linaro 4.7.4 Toolchain

Change-Id: Iac0e1deb2f030b283c9dc858d290552b345d4689
Rom : Use -O3 for Optimization

Change-Id: I63db46028d7ed54a72e5b23ea58095778fc5c69d
Disable -Wunused-parameter

Change-Id: I4289c7d97d1d9694dd74f23d2e0fee07d2374e67
Kernel : Use Linaro 4.8.2 Toolchain

Change-Id: I25f67548af4244c20179437ad4ee0c68aaf8213a