imx6: drop duplicated bss memset and board_init_r() call

imx6: drop duplicated bss memset and board_init_r() call

bss section is cleared in crt0.S. board_init_r() is also
entered from crt0 code.

Signed-off-by: Anatolij Gustschin <[email protected]>
Cc: Christian Gmeiner <[email protected]>
Cc: Nikita Kiryanov <[email protected]>
Cc: Jagan Teki <[email protected]>
Cc: Tim Harvey <[email protected]>
Cc: Marek Vasut <[email protected]>
Cc: Lukasz Majewski <[email protected]>
Cc: Fabio Estevam <[email protected]>
Reviewed-by: Lukasz Majewski <[email protected]>
Reviewed-by: Christian Gmeiner <[email protected]>
Reviewed-by: Fabio Estevam <[email protected]>