riscv: Move mcall numbers to mcall.h, adjust their names

The new name and location make more sense:

 - The instruction used to call into machine mode isn't called "ecall"
   anymore; it's mcall now.
 - Having SBI_ in the name is slightly wrong, too: these numbers are not
   part of the Supervisor Binary Interface, they are just used to
   forward SBI calls (they could be renumbered arbitrarily without
   breaking an OS that's run under coreboot).

Also remove mcall_dev_{req,resp} and the corresponding mcall numbers,
which are no longer used.

Change-Id: I76a8cb04e4ace51964b1cb4f67d49cfee9850da7
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/18146
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
5 files changed