powerpc/pseries: Remove confusing warning message.

Since commit 1211ee61 ("powerpc/pseries: Read TLB Block Invalidate
Characteristics"), a warning message is displayed when booting a guest
on top of KVM:

  lpar: arch/powerpc/platforms/pseries/lpar.c pseries_lpar_read_hblkrm_characteristics Error calling get-system-parameter (0xfffffffd)

This message is displayed because this hypervisor is not supporting
the H_BLOCK_REMOVE hcall and thus is not exposing the corresponding
feature.

Reading the TLB Block Invalidate Characteristics should not be done if
the feature is not exposed.

Fixes: 1211ee61 ("powerpc/pseries: Read TLB Block Invalidate Characteristics")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191001132928.72555-1-ldufour@linux.ibm.com

arch/powerpc/platforms/pseries/lpar.c

@@ -1419,6 +1419,9 @@ void __init pseries_lpar_read_hblkrm_characteristics(void)
 	unsigned char local_buffer[SPLPAR_TLB_BIC_MAXLENGTH];
 	int call_status, len, idx, bpsize;
 
+	if (!firmware_has_feature(FW_FEATURE_BLOCK_REMOVE))
+		return;
+
 	spin_lock(&rtas_data_buf_lock);
 	memset(rtas_data_buf, 0, RTAS_DATA_BUF_SIZE);
 	call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,