arm: spl: Add I2C linker list in generic .lds

arm: spl: Add I2C linker list in generic .lds

On LS1, DDR is initialized by reading SPD through I2C interface
in SPL code. For I2C, ll_entry_count() is called, and it returns
the number of elements of a linker-generated array placed into
subsection of .u_boot_list section specified by _list argument.
So add I2C linker list in the generic .lds to fix the issue about
using I2C in SPL.

Signed-off-by: Alison Wang <alison.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>