syscall_emul: update arm uname release to 3.7.0+

syscall_emul: update arm uname release to 3.7.0+

Trying to compile an ARM C hello world with arm-linux-gnueabihf-gcc from
Ubuntu 16.04 leads to a runtime failure with se.py:

FATAL: kernel too old

because the glibc tests if the kernel is at least 3.2.0, and gem5 was
reporting 3.0.0.

Furthermore, it is hard to obtain such toolchain at all: for example
crosstool-NG currently only allows for minimum kernels above 3.2.0.

3.7.0+ was chosen to match the aarch64 value, as it is likely that the
level of support will be very similar.

This commit does not guarantee that full 3.7.0 is supported, but it is
not likely that we had full 3.0.0 support previously either.

However, it is more likely that such support will be eventually achieved
if users can at least try out their programs and implement the missing
system calls as they are found.

Change-Id: I8df3763ae49788a6cb11cb0920e8202cd56b0f09
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/12986
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>