init: fix in-place parameter modification regression

init: fix in-place parameter modification regression

Before commit 026cee0086fe1df4cf74691cf273062cc769617d
("params: <level>_initcall-like kernel parameters") the __setup
parameter parsing code could modify parameter in the
static_command_line buffer and such modifications were kept. After
that commit such modifications are destroyed during per-initcall level
parameter parsing because the same static_command_line buffer is used
and only parameters for appropriate initcall level are parsed.

That change broke at least parsing "ubd" parameter in the ubd driver
when the COW file is used.

Now the separate buffer is used for per-initcall parameter parsing.

Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>