Convert the following chips to block_erasers:
SST28SF040A
SST29EE010
SST29LE010
SST29EE020A
SST29LE020
SST39SF010A
SST39SF020A
SST39SF040
SST39VF512
SST39VF010
SST39VF020
SST39VF040
SST39VF080
SST49LF002A/B
SST49LF003A/B
SST49LF004C
SST49LF008A
SST49LF008C
SST49LF016C
SST49LF020
SST49LF020A
SST49LF040
SST49LF040B
SST49LF080A
SST49LF160C

Extend sst28sf040 to include chip and sector functions for block_eraser.
Extend sst49lfxxxc to include chip, sector, block erasers functions for block_erasers.
Extend sst_fwhub to include chip and sector functions for block_erasers.
Add copyrights to changed files.
Killed erase_sst_fwhub.
Killed erase_49lfxxxc.
NULL A/A mux mode full chip erasers.
Ignore block locks in erase/write.
Change comments from "PP mode" to "A/A mux mode"

Signed-off-by: Sean Nelson <audiohacked@gmail.com>