ARM: davinci: avoid unused mityomapl138_pn_info variable

The mityomapl138_pn_info structure belongs into the CPU_FREQ support
that is hidden behind an #ifdef, and causes a harmless warning when
that support is disabled:

mach-davinci/board-mityomapl138.c:59:28: error: 'mityomapl138_pn_info' defined but not used [-Werror=unused-variable]

This moves the variable definition where it belongs.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>