leds: qpnp-flash-v2: Add support for multi-strobe

Multi-strobe option is used to enable/disable the LEDs
back-to-back without disabling the module in the HW_STROBE mode.
Hence, enable the multi-strobe option if the LED is configured
in HW_STROBE mode.

Change-Id: I3e16254c6dcb4c4ae0b295cd7eea4e8ee8e1c2c7
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>