msm: mdm: do not reset the external modem on second power up

It is not necessary to reset the external modem the second time
it is being powered up because it has already been powered up for
early initialization.

Change-Id: I9837aa3b26d442f1521b5919d8f2c0f2080297a5
Signed-off-by: Joel King <joelking@codeaurora.org>