Rename legacy-specific structures and macros with legacy prefix; rename
smc-specific structures and macros with smc prefix. This should make it
clearer which structures are generic to "SCM" and which are specfically
for implementing the convention.

Tested-by: Brian Masney <masneyb@onstation.org> # arm32
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
Link: https://lore.kernel.org/r/1578431066-19600-2-git-send-email-eberman@codeaurora.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>