kcov: remove stale RANDOMIZE_BASE text

The Kconfig help text for CONFIG_KCOV describes that recorded PC values
will not be stable across machines or reboots when RANDOMIZE_BASE is
selected. This was the case when KCOV was introduced in commit:

5c9a8750a6409c63 ("kernel: add kcov code coverage")

However, this changed in commit:

4983f0ab7ffaad1e ("kcov: make kcov work properly with KASLR enabled")

Since that commit KCOV always subtracts the KASLR offset from PC values,
which ensures that these are stable across machines and across reboots
even when RANDOMIZE_BASE is selected.

Unfortunately, that commit failed to update the Kconfig help text, which
still suggests disabling RANDOMIZE_BASE even though this is no longer
necessary.

Remove the stale Kconfig text.

Link: https://lkml.kernel.org/r/20231204171807.3313022-1-mark.rutland@arm.com
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>