configs: ti: Factor out call to 'args_mmc' into MMC common environment

Both 'loadfit' and 'mmcloados' start with a call to 'args_mmc' so this
can be factored out to before eithers only call site. This also allows us
to remove that call from 'loadfit', which should not have been calling it
anyway as that command should not be MMC specific. Without the call to
'args_mmc' the command 'loadfit' becomes just a call to 'run_fit' so
remove the indirection and call 'run_fit' directly, this removes the need
for 'loadfit' command (which was misnamed anyway). Drop it.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>