hwrng: drivers - add missing Arm & Cavium MODULE_DESCRIPTION() macros
With ARCH=arm64, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/char/hw_random/cavium-rng.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/char/hw_random/cavium-rng-vf.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/char/hw_random/arm_smccc_trng.o
Add the missing invocations of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>