CONFIG_SYS_GBL_DATA_SIZE is not used any more.
The size of struct "global_data" is automatically calculated
by asm-offsets. (See lib/asm-offsets.c)

GENERATED_GBL_DATA_SIZE should be used instead of
CONFIG_SYS_GBL_DATA_SIZE.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>