configs: change hostname from "turing pi" to "turingpi"

Hostnames cannot contain spaces. See hostname(7):

> Each element of the hostname must be from 1 to 63 characters  long  and
> the  entire hostname, including the dots, can be at most 253 characters
> long.  Valid characters for hostnames are ASCII(7) letters from a to z,
> the  digits  from 0 to 9, and the hyphen (-).  A hostname may not start
> with a hyphen.

This causes problems when using, for example, hostname(1).

tp2bmc/configs/tp2bmc_defconfig

@@ -14,7 +14,7 @@ BR2_TOOLCHAIN_EXTERNAL_GCC_7=y
 BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_10=y
 BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
 BR2_TOOLCHAIN_EXTERNAL_CXX=y
-BR2_TARGET_GENERIC_HOSTNAME="turing pi"
+BR2_TARGET_GENERIC_HOSTNAME="turingpi"
 BR2_TARGET_GENERIC_ISSUE="Welcome to Turing pi"
 BR2_INIT_SYSV=y
 BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y