fmc: remove left-over ipmi-fru.h after fmc deletion

fmc: remove left-over ipmi-fru.h after fmc deletion

Commit 18ece546a5b4 ("fmc: Delete the FMC subsystem") from Linus Walleij
deleted the obsolete FMC subsystem, but missed the MAINTAINERS entry and
include/linux/ipmi-fru.h mentioned in the MAINTAINERS entry.

Later, commit 0aa0a5c3c8b5 ("MAINTAINERS: Remove FMC subsystem") from
Denis Efremov cleaned up the MAINTAINERS entry, but actually also missed
that include/linux/ipmi-fru.h should also be deleted while deleting its
reference in MAINTAINERS.

So, deleting include/linux/ipmi-fru.h slipped through the previous
clean-ups.

As there is no further use for include/linux/ipmi-fru.h, finally delete
include/linux/ipmi-fru.h for good now.

Fixes: 0aa0a5c3c8b5 ("MAINTAINERS: Remove FMC subsystem")
Fixes: 18ece546a5b4 ("fmc: Delete the FMC subsystem")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20191214114913.8610-1-lukas.bulwahn@gmail.com
Acked-by: Federico Vaga <federico.vaga@cern.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>