auxdisplay: Kconfig: drop unneeded quotes in PANEL_BOOT_MESSAGE dep

auxdisplay: Kconfig: drop unneeded quotes in PANEL_BOOT_MESSAGE dep

The PANEL_BOOT_MESSAGE dependency uses a quoted-string comparison
against the PANEL_CHANGE_MESSAGE bool symbol:

	depends on PANEL_CHANGE_MESSAGE="y"

This is the only such pattern under drivers/auxdisplay/ (grep shows
no other Kconfig file in the tree uses depends on FOO="y" with
quotes for a plain bool symbol). The quoted form is parsed by
Kconfig but is not idiomatic; the common form for the same intent
is the unquoted tristate-style dependency:

	depends on PANEL_CHANGE_MESSAGE

which evaluates true when PANEL_CHANGE_MESSAGE is y or m. Since
PANEL_CHANGE_MESSAGE is declared as bool (not tristate), there is
no behaviour change in practice: y is the only enabled value
either form can match.

Drop the quoted comparison so the dependency matches the prevailing
kernel Kconfig style and so it is obvious to readers that the
comparison works.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/CAHp75VfsA_LsbEKjxoeMdbhPbWj7OHZ7=0SYNA3c=ZLj_M94Bw@mail.gmail.com
Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>