ARM: dts: ti: Fix node name for all ecap dt nodes

dtbs_check produces the following warning for ecap node name:
ecap@100: $nodename:0: 'ecap@100' does not match '^pwm(@.*|-[0-9a-f])*$'

Fix this by replacing ecap with pwm in node name

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>