powerpc/head_check: Avoid broken pipe

Remove the '-m4' option to grep to allow grep to process all of nm's
output.  This avoids the nm warning:

  nm terminated with signal 13 [Broken pipe]
Signed-off-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/872b6c84a4250ff140e476c62cabe9e56a02b6c2.1589049250.git.geoff@infradead.org

arch/powerpc/tools/head_check.sh

@@ -46,7 +46,7 @@ nm="$1"
 vmlinux="$2"
 
 # gcc-4.6-era toolchain make _stext an A (absolute) symbol rather than T
-$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" -m4 > .tmp_symbols.txt
+$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" > .tmp_symbols.txt
 
 
 vma=$(cat .tmp_symbols.txt | grep -e " [TA] _stext$" | cut -d' ' -f1)