omap2+: Remove useless Makefile line

Merge commit 95241450 ("Merge branch
'next/cleanup' of git://git.linaro.org/people/arnd/arm-soc"

) added
references to CONFIG_MACH_PCM049 and board-omap4pcm049.o to this
Makefile. But there's no Kconfig symbol MACH_PCM049 and there's no file
board-omap4pcm049.c. This line can safely be removed.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Tony Lindgren <tony@atomide.com>