[WATCHDOG] Fix declaration of struct smbios_entry_point in hpwdt

On my HP DL380 G5 system running a 64-bit kernel, loading the hpwdt
driver causes a crash because the driver attempts to ioremap an
invalid physical address.  This is because the driver has an incorrect
definition of the SMBIOS table entry point structure: the table
address is only a 32-bit quantity, and making it a u64 means that the
high-order 32 bits end up containing garbage.

Correcting the structure definition fixes the driver so that it loads
without any problems on my system.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Acked-by: Thomas Mingarelli <Thomas.Mingarelli@hp.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>