msm: irqs: Remove per-target IRQ files for 8910 and 8226

Since the per-target IRQ files for 8910 and 8226 have been
reduced to one line, remove these files and move the only
remaining definition into the common IRQ file until this
definition is removed entirely.

Change-Id: I24981042cacb27b7299cf8d00f7d6f8eee594167
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>