Merge tag 'mips-pull-2018-11-18' of git://git.denx.de/u-boot-mips

- tree-wide: introduce LDFLAGS_STANDALONE
- MIPS: fix long-standing issue with linking of standalone programs
- MIPS: MT76xx: add GPIO and WDT drivers
- MIPS: MT76xx: various fixes and updates to gardena-smart-gateway board
- MIPS: MT76xx: various fixes and updates to linkit-smart-7688 board