x86: fix bogus memcpy in es7000_check_dsdt()

es7000_check_dst() contains a memcpy from 0, which probably should have been
a memset. Remove it and check the retunr value from acpi_get_table_header.

Noticed by: Joe Perches <joe@perches.com>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>