platform/x86: thinkpad_acpi: Replace ifdef CONFIG_ACPI_PLATFORM_PROFILE with depends on

With the #if IS_ENABLED(CONFIG_ACPI_PLATFORM_PROFILE), we get the following
errors when thinkpad_acpi is builtin while CONFIG_ACPI_PLATFORM_PROFILE=m :

drivers/platform/x86/thinkpad_acpi.c:10186: undefined reference to `platform_profile_notify'
drivers/platform/x86/thinkpad_acpi.c:10226: undefined reference to `platform_profile_register'
drivers/platform/x86/thinkpad_acpi.c:10246: undefined reference to `platform_profile_remove'

This could be fixed by changing the IS_ENABLED to IS_REACHABLE, but
I believe that it is better to just switch to using depends on.

Using depends on ensures that platform-profile support is always
available when thinkpad_acpi is build, hopefully leading to less
confusing bug-reports about it sometimes not working.

Cc: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210204140158.268289-2-hdegoede@redhat.com