grant_table: use term 'mfn' for machine frame numbers...
...rather than more ambiguous term 'frame'.
There are many places in the grant table code that use a variable or
field name '.*frame' to refer to a quantity that is strictly an MFN, and
even has type mfn_t.
This patch is a purely cosmetic patch that substitutes 'frame' with 'mfn'
in those places to make the purpose of the variable or field name more
obvious.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: George Dunlap <George.Dunlap@eu.citrix.com>