asm-generic: global_data: change timebase_l/h to unsigned int

asm-generic: global_data: change timebase_l/h to unsigned int

Change type of timebase_l/h to unsigned int.
>From lib/time.c: ((uint64_t)gd->timebase_h << 32) | gd->timebase_l;
This piece code is based on that timebase_h and timebase_l are
32bits width, so change the type to unsigned int.

Signed-off-by: Peng Fan <[email protected]>
Cc: Eddie Cai <[email protected]>
Cc: Jagan Teki <[email protected]>
Cc: York Sun <[email protected]>
Cc: "Robert P. J. Day" <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Tom Rini <[email protected]>
Reviewed-by: Simon Glass <[email protected]>