ARM: dts: Fix am33xx.dtsi ti,sysc-mask wrong softreset flag

AM335x TRM: Figure 16-23 define sysconfig register and soft_reset
are in first position corresponding to SYSC_OMAP4_SOFTRESET defined
in ti-sysc.h.

Fixes: 0782e857 ("ARM: dts: Probe am335x musb with ti-sysc")
Signed-off-by: Oskar Holmlund <oskar@ohdata.se>
Signed-off-by: Tony Lindgren <tony@atomide.com>