bdinfo: Rename function names to be clearer

At present we have bdinfo_print_num() to print unsigned long numbers.
We also have print_phys_addr() which accept numbers that might be
64-bit on a 32-bit platform.

Rename these 2 functions to be clearer:

bdinfo_print_num() => bdinfo_print_num_l()
print_phys_addr()  => bdinfo_print_num_ll()

While we are here, make bdinfo_print_num_ll() public so that it can
be used outside cmd/bdinfo.c in the future.

Signed-off-by: Bin Meng <bin.meng@windriver.com>