interconnect: qcom: Fix small BW votes being truncated to zero

Small BW votes that translate to less than a single BCM unit are
currently truncated to zero. Ensure that non-zero BW requests always
result in at least a vote of 1 to BCM.

Change-Id: I144b22c11d19e29bebd19685b4d1a0e2b14a6abd
Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>