msm: ipa: fix boot crash

IPA debugfs file creation function can run before probe of
platform driver is called and the former assumes IPA context
is allocated which happens only after latter. This commit fixes
this sequencing bug.

Change-Id: Iadca31bd7869aa33b6dee53f9ce2066617c67109
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>