clk: ti: dra7: fix kernel boot with arg 'clocksource=gp_timer'

The OMAP Platform code provides possibility to select GP Timer as
default clocksource instead of counter_32K by using bootcmd parameter
'clocksource', but the system will crash during early boot when this
option is used on dra7 or omap5 platforms, because it will hit BUG()
statement:

 omap2_gptimer_clocksource_init
  ->BUG_ON(res);

This happens because clk_dev alias "sys_clkin_ck" is not registered.
Hence, fix it by adding missing "sys_clkin_ck" clk_dev aliases
definitions for omap5 and dra7.

Acked-by: Tero Kristo <t-kristo@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>