OMAP: Tweak omap-common/Makefile since reset.S -> reset.c
Git commit d417d1db5f9092d125ddea882ced77eaa5f3d236 replaced the
omap-common file reset.S with reset.c, but the Makefile was not
adjusted for that.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>