MIPS: TXx9: Fix build error if CONFIG_TOSHIBA_JMR3927 is not selected

MIPS: TXx9: Fix build error if CONFIG_TOSHIBA_JMR3927 is not selected

The jmr3927_vec txx9_board_vec struct is defined in
txx9/jmr3927/setup.c which is only built if
CONFIG_TOSHIBA_JMR3927 is selected. This patch fixes the following
build problem:

arch/mips/txx9/generic/setup.c: In function 'select_board':
arch/mips/txx9/generic/setup.c:354:20: error:
'jmr3927_vec' undeclared (first use in this function)
arch/mips/txx9/generic/setup.c:354:20: note: each undeclared
identifier is reported only once for each function it appears in
make[3]: *** [arch/mips/txx9/generic/setup.o] Error 1

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5713/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>