Changes to support AMP BSP

- Disable CONFIG_CC_OPTIMIZE_FOR_SIZE to use -O2 optimization
- Add a SBT_BSP select in Config for normal "SDRDC" vs AMP "SDRDC-AMP" BSP
- Remove Kconfig.lib.auto/Makefile.lib.auto generation now that Petalinux _defconfig
  works, was causing lib rebuild problems with readline.
- Revise setup/defconfig logic:
  - Move mrproper/defconfig from build to reset step
  - Call manually with reset target, or from setup target based on flag file
- Calculate uImage LOADADDR based on CONFIG_PHYS_OFFSET if enabled and >0, for AMP
- Change Petalinux "make dep" on kernel sources to "make prepare"
- Remove various verbose and debug messages
Merge branch 'sdrdc-devel' of https://github.com/silverbullettechnology/sdrdc-build into sdrdc-devel