correct console log level when ERST ACPI table is not found

When booting 2.6.35-rc3 on a x86 system without an ERST ACPI table with
the 'quiet' option, we still observe an "ERST: Table is not found!"
warning.

Quiesce it to the same info log level as the other 'table not found'
warnings.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>