Making Coreboot Coverity Clean

The coreboot project is automatically scanned by Coverity, a free static-analysis tool provided by Synopsis to open source projects. This tool analyzes the source code to check for common mistakes and errors, including static buffer overruns, null pointer dereferences, integer overflow, and other suspicious code. The coreboot project currently has over 380 flagged Coverity issues. The goal of this project is to make coreboot "Coverity clean". All outstanding issues will be classified, invalid reports will be marked as false-positives, and valid ones will be patched. This will address all issues with the current codebase, and ensure a common baseline for triaging new issues in the future.