wifi: rtw88: debugfs: support multiple adapters debugging

Originally in order to read partial registers from large area, we write
a range value stored into a static variable and read registers according
to the static variable.

However, if we install more than one adapters supported by this driver,
the static variables will be overwritten by latter adapters. To resolve
the problem, move the static variables to struct rtw_dev for each adapter.

With changes, smatch spends too much time to parse rtw_debugfs_init():
    debug.c:1289 rtw_debugfs_init() parse error: turning off implications
    after 60 seconds
Move stuffs of adding debugfs entries to three rtw_debugfs_add_xxx()
functions.

Reported-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Closes: https://lore.kernel.org/linux-wireless/cd6a2acf3c2c36d938b40140b52a779516f446a9.camel@realtek.com/T/#m27662022c70d9f893ba96f6c6a8dd8fce2434dfe


Tested-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20240718064155.38955-1-pkshih@realtek.com