mmc: host: Fix the condition to parse crypto clocks

If crypto clock details are present the call returns 0 which must
be checked to parse the clock entry in host controller dtsi node.

Test: 1. Clock scalability.
      2. Performance number using Andorbench apk.

Change-Id: I10ee3de1c1e02299de6ab390852d367cdb303224
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>