fs_context: fix parameter name in infofc() macro

fs_context: fix parameter name in infofc() macro

The macro takes a parameter called "p" but references "fc" internally.
This happens to compile as long as callers pass a variable named fc,
but breaks otherwise. Rename the first parameter to “fc” to match the
usage and to be consistent with warnfc() / errorfc().

Fixes: a3ff937b33d9 ("prefix-handling analogues of errorf() and friends")
Signed-off-by: RubenKelevra <rubenkelevra@gmail.com>
Link: https://lore.kernel.org/20250617230927.1790401-1-rubenkelevra@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>