Remove mbed-os library
Remove mbed-os library

This commit reverts the addition of an mbed-os.lib file introduced with the Mbed-OS port. Mbed-OS build tools use .lib files to pull in additional dependencies automatically with a single command. The intended usage of mcuboot with mbed-os is to clone mcuboot *next to* mbed-os, rather than mbed-os inside mcuboot.

Signed-off-by: George Beckstein <3dff0068d8259b9ae11f2c1aef3f183fbdff9922@embeddedplanet.com>

runtimeco/mcuboot,runtimeco/mcuboot,utzig/mcuboot,utzig/mcuboot,utzig/mcuboot,utzig/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,utzig/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot