parisc: Detect hppa-suse-linux-gcc compiler for cross-building

Allow the system to find the SUSE hppa compiler and linker to set
CROSS32_COMPILE and CROSS_COMPILE.

Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>