mfd: ti_am335x_tscadc: Fix merge issue

Commit e823ec6f removed the udelay in the interrupt handler.
But a merge error occurred when it got merged by pulling v3.14.24, which
can lead to a task lock-up.
This commit fixes the merge error.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>