ARM: at91: remove useless init_time for DT-only SoCs

Commits bcf8c7e7 and
4bf7753b introduced compilation errors
("error: 'NR_IRQS_LEGACY' undeclared (first use in this function)") because
they remove the asm/irq.h inclusion while the init_time function needs it
for the NR_IRQS_LEGACY definition.

In the other hand, the point of these commits is to remove board file
support, and init_time is only needed when booting non-DT boards, we can
thus safely remove init_time functions.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>