Though the thread is very old, just to update.
The error log seems that, the file 'kernel_imx/arch/arm/configs/imx_v7_android_defconfig' is not present in your android source tree.
Possibly issue could be either of below,
1. the imx6 kernel code at kernel_imx folder is not present.
2. the kernel code is not checked out to the release version.
First go to your android code and check 'ls -l kernel_imx/arch/arm/configs/imx_v7_android_defconfig'
And check whether the file is present.
If you find the file, there should not be a problem.