hw/eeprom93xx.c: support 93xx EEPROMs with more than 255 words

hw/eeprom93xx.c: support 93xx EEPROMs with more than 255 words

In the head of eeprom93xx.c we promise to support chips with 256 words,
but store the size in an unsigned byte. This patch replaces this with an
16 bit variable and changes the load/store code accordingly (introducing a
new version).

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6918 c046a42c-6fe2-441c-8c8c-71466251a162