random: Avoid open-coded use of ratelimit_state structure's ->missed field

random: Avoid open-coded use of ratelimit_state structure's ->missed field

The _credit_init_bits() function directly accesses the ratelimit_state
structure's ->missed field, which works, but which also makes it
more difficult to change this field.  Therefore, make use of the
ratelimit_state_get_miss() and ratelimit_state_inc_miss() functions
instead of directly accessing the ->missed field.

Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@web.de/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
"Jason A. Donenfeld" <Jason@zx2c4.com>