klibc: Fix build issue when default ISA is not thumb

We were passing empty string '' to make as option when
ISA was not thumb this breaks build for machines/distros
which do not use ARM_INSTRUCTION_SET = thumb

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
(cherry picked from commit cafe21e8a20610deffa3b79af223b939518ef9a8)
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-initramfs/recipes-devtools/klibc/klibc.inc

@@ -42,7 +42,7 @@ EXTRA_OEMAKE = "'KLIBCARCH=${KLIBC_ARCH}' \
                 "
 
 export FIX_ARMV4_EABI_BX = "${FIX_V4BX}"
-KLIBCTHUMB = "${@['', 'CONFIG_KLIBC_THUMB=y'][(d.getVar('ARM_INSTRUCTION_SET') == 'thumb')]}"
+KLIBCTHUMB = "${@['CONFIG_KLIBC_THUMB=n', 'CONFIG_KLIBC_THUMB=y'][(d.getVar('ARM_INSTRUCTION_SET') == 'thumb')]}"
 
 do_configure () {
     ln -sf "${STAGING_DIR_TARGET}${exec_prefix}" linux